IN the case or restorations, what's on the car now (if it's unmolested) would be the most correct for THAT particular vehicle.
There CAN be a lot of good information in the books, though.
As for the "orange" engine colors, my evolving theory is that ONLY the cars with the 268/284 (original '67 GTX/'68 Road Runner) cams were painted orange, other than the 426 Street HEMI. Others, even if termed "high performance" in the sales literature, but not have the genuine HP camshaft and such, were painted the corporate color for the model year. Which would explain why my '70 Monaco "N" (and Carter AVS, regular 4bbl cam) is painted OEM blue, but a '70 Road Runner "N" (and Holley 4bbl) would have been orange. Of course, the "orange" would be "Street HEMI Orange".
I'd heard the issue of orange vs blue, automatic vs manual, a/c or not, for years, but when I was looking through the AMA Specs (at
www.hamtramck-historical.com) for '70 specific cars, when a 'Cuda 383 "N" was different from a "70 Barracuda "N", or a '70 Satellite "N" was different from a '70 Road Runner 383 "N", THAT's where the issue of color came into perspective (as did the related camshaft specs)!
On the assembly lines, the predominant way to identify "things" was with colors and color code stripes, NOT numbers specifically, although assembly instructions (build manuals) might define them as color codes and option code/assembly numbers. Still, "color codes" were what determined what was put in a particular vehicle. Therefore, with an engine hanging on the hook at the "engine drop" part of the line, it was much easier to see color at a glance, rather than stop to check numbers. Now, IF the person loading the conveyor for the engines might get one our of sequence, but they were still "383 4bbl "N", that's how it went to the line, with no time to change it if the issue was discovered at the last second. In which case, the "mistake" lived on into the restoration realm decades later.
The color and type issue also explains why the car might have the correct interior in it (model, style, and color) but have the build sheet attached to it for a different VIN. It was grabbed by visuals rather than looking for the build sheet and matching the VIN. Which is something we had discovered to have happened when build sheets became important information tools in the 1980s. When the retrieved build sheets for a particular car didn't match the VIN of the car they were found in.
Which makes my "268/284 cam = orange be pretty reasonable to me. BTAIM.
Might have to do some looking on the undersides of the block and such to see if parts of the engine still have the OEM paint on them. Air cleaner would be the same semi-gloss/satiny black paint as the engine (alternator belt adjusting, power steering pump and brackets, plus pulleys) brackets and a/c compressor.
One reason for the "differences" in what some books might claim and what came out on the cars was due to the issue of "keeping the line running" and (in the noted case of engine colors) using up what was "in stock" for paint if the correct paint might not have been available when it was needed. "Paint" was more for rust prevention on the cast iron castings rather than for strict cosmetics (as on exterior body panels).
Before all of the more recent restoration paints came available (like in 1981), we got some color swatches and the '66 Dodge pickup color "Desert Turquoise" matched the engine color of my '67 Newport perfectly. Got a small amount mixes in acrylic enamel. Painted the new oil pan of rthat car with it. Sprayed the new pan with B-12 (in pre-spray brake cleaner days), cut it with some generic enamel reducer from Home Depot, then used a (then new on the market) Pre-Val glass jar spray unit to apply it. Worked out well and it still shines like new.
By comparison, engine enamel was pretty inexpensive-type enamel. Not acrylic enamel, typically. Enough shine to look decent and cover the cast iron for rust prevention.
Enjoy!
CBODY67