All of the General Motors engine compartments are very similar. Each division may have made small changes to suit their individual applications, and each have their own engine colors, but the major components color of parts, and plating that are used remain essentially the same. I would emphasize that research is the key. When you take your engine out for rebuilding or detailing, photograph the components before they are disassembled. Remove the parts and note whether they are plated, painted, or just natural. When the car is being reassembled the parts should be returned to their original condition. Through research it's been discovered that the following components should be restored as shown. Naturally there are always exceptions for a given year but these can be used as a guideline.

Good "Chevrolet Orange" in spray cans is either Plasti-Kote 200 or Duplicolor 1620.

Accelerator rod, accelerator lever:
Black oxide.

Alternator:
Natural aluminum finish, no paint or plating.

Alternator fan:
Zinc plated (silver or green/gold).

Alternator pulley:
Silver cad plated or gold cad plated (depending upon the application). Most plating shops can handle either application.

Battery box hold down clamp:
Semi-gloss black.

Brake distribution bracket:
Cadmium dichromate.

Brake lines:
Natural steel, no paint or plating.

Brake line clips:
We've seen these clips in natural finish, black oxide, and zinc chromate (green) finish.

Clutch cross shaft:
Gray phosphate plate.

Clutch linkage parts:
Gloss black finish.

Clutch fork:
Natural steel finishes that can be painted with cast-iron spray paint.

Clutch return spring:
Natural steel or gray phosphate.

Clutch return spring bracket:
Natural steel finish.

Control arm cross shafts:
Semi-gloss black enamel.

Control arm bolts and large-end washers:
Natural steel.

Control arm adjustment shims:
Natural steel.

Engine accessory braided ground strap:
Natural, no paint or plating.

Engine dipstick handle:
Natural steel finish.

Exhaust manifolds:
This is another area where the GM divisions differed. According to restoration sources, Chevrolet exhaust manifolds were over-sprayed when the engine was painted. According to Pontiac sources, Pontiac engines were painted first, then the exhaust manifolds was installed. Whatever the case may be, if you are going to drive the car, any over-spray that may be sprayed on the exhaust manifolds will burn off quickly.

Exhaust manifold locks:
The exhaust manifold locks were natural finish unless the exhaust manifolds were painted; then they were over-sprayed.

Fan blades:
Fans on GM cars differed from brand to brand. Some divisions, like Chevy, painted the fan and blades black, while other GM divisions used natural stainless fan blades with black center hubs. If the fan was a clutch-type, the clutch was natural aluminum with a gold cadmium center. The clutch shaft and spring are natural finish.

Fender bolts, fender bolt washers:
Black oxide.

Frame or sub frame:
The frame and sub frame on all Sixties through Seventies GM muscle cars were painted semi-gloss black. Some restorers like the frames a little more on the shiny side, while others like a flatter finish. There are a lot of different formulas for this and different paints you can use. Most restorers use acrylic enamel or acrylic urethane finishes with a flattening agent for frame components because of their durability, One formula that you can use is as follows:
3 qt. PPG Delstar mixing black
1 qt. flattening agent
PPG DTR601 quick-dry reducer

Front springs:
Natural metal.

Fuel lines:
Natural steel finish, no paint or plating,

Heater/heater shroud:
Semi-gloss to gloss black lacquer. Generally, more shine than the engine compartment.

Hood hinges, hood latch, hood catch, hood springs:
These components look like they are natural finish, but they were actually gray phosphate plated. This process is available from several plating companies. Upper and lower alternator brackets: Most pulleys and brackets used  on GM cars were painted semi-gloss black, but there are some exceptions to the rule. Research your particular car because on some GM brands, individual pulleys could have also been gray phosphates, zinc, or cad plated. Some of the GM divisions also used large aluminum brackets that were natural aluminum in color.

Horns:
Gloss black finish.

Horn relay:
Natural, no paint.

Ignition wire dividers:
Black plastic.

Inner fenders, firewall, under hood, radiator support:
As with the frame, there are many different formulas that can be used to achieve a semi gloss black paint to match the factory finish. Some restorers like to mix their own paint to get the shine they desire, but many restorers also use a premixed PPG paint for their engine compartment. We have used PPG 9423 lacquer on our cars and it is about as close as you can get to the factory finish and, typically, a quart is enough to do a complete engine compartment. Many of the spray can manufacturers (e.g. Krylon, VHT) make a semi-gloss black that also looks good on engine compartment components if you don't have professional spray painting equipment. If you have spray equipment here's another custom lacquer formula that you can use:
2 qt. PPG mixing black #386
1 qt. universal flattening agent
1 qt. mixing clear #3 10
PPG DTL16 thinner

Master cylinder:
Most of the GM cars came with natural finish master cylinders. For a lasting natural look, they can be painted with cast-iron gray paint, which is available from a variety of sources such as The Eastwood Company, VHT, and Krylon.

Master cylinder lid:
The master cylinder lid should be cadmium dichromate (gold rainbow cad This type of plating is available from several sources. The master cylinder bail clips are natural metal.

PCV- hose clips:
Black oxide.

Power brake booster:
All GM power brake boosters were cadmium dichromate. The two companies mentioned above can rebuild and re-plate your power-booster.

Power brake hose clips:
Black oxide.

Power steering pump:
Gloss black enamel.

Power steering brackets:
Semi-gloss black enamel. Some brackets may actually look like a cross between semi-gloss and gloss black.

Radiator:
All GM cars of this era had Harrison radiators that were painted gloss black.

Radiator cap:
Radiator caps were not painted, they were plated.

Radiator shroud:
Radiator shrouds should be left natural plastic. Some shrouds on early GM cars were steel and they should be painted semi-gloss to gloss black.

Shock absorbers:
Gloss gray enamel.

Steering box:
The cast-iron portion of the box is natural finish. The access lid is natural aluminum; the bolts are black oxide.

Stabilizer bar:
Depending upon the GM division, these can be natural or semi-gloss black.

Stabilizer bar brackets:
Depending upon the GM division and supplier, the brackets can be semi-gloss black or natural.

Tie rods, steering components:
Natural steel finish. These components can be painted with clear or cast-iron colored paint.

Voltage regulator cover:
Gloss-black enamel.

Water pump pulley, crankshaft pulley:
Semi-gloss black, some crank pulleys were cast and left natural finish. Some water pump pulleys on early GM muscle cars were zinc plated.

Windshield wiper motor:
Gloss black finish.