TLDR; If you want a good approximation for black engine paint on a Porsche 914 Prismatic Powders Card Black is a good choice for powder coat. Dupli-color Semi-Gloss Black Engine Enamel with Ceramic DE1635 is a decent spray can match for things you can’t powder coat (e.g. starter motors).
Similar to the exercise I did on our 356, I tested a variety of paint samples against car components to see if I could find a close match. I wanted one choice in the form of powder coat and another from a spray can. For powder coat, I stuck with Prismatic Powders line. You can get quantities as low as 1 lb. and they have many choices of color and sheen. They will send you samples. I started with roughly 8 different options from them, and narrowed final selection from four. Spray can was a large assortment of paint from consumer name brands and auto specialists. This included Eastwood, Wurth, Stoddard, Dupli-color, Krylon, etc. I shot them on some old engine tin I wasn’t planning to put back on the car. I narrowed it down to two and made a final selection from those.
Over the years, Porsche used a lot of different vendors. So it’s unlikely that all the black components on the car were the same type of paint, much less the same shade. For sanity, I just picked a couple of parts that seemed to have survived pretty well for 50+ years and use them as my benchmark. They were a covered part from the CDI mounting bracket, and what I believe to be an original starter motor. I looked under different lighting conditions (e.g. soft white-2700K, cool white 5000K, and natural daylight). Given that any sheen they had was likely to have worn away to a large degree, I did some spot tests wet just to see how much it changed things.
I prioritized shade of black, then looked for sheen. Since I suspect most vintage cars will be viewed in daylight, or perhaps well lit garages, I prioritized natural daylight and then 5000K cool white light (popular LED lighting).
