This question was also posted on the CJ for input from those members. There was a request or question if there were any period pictures that showed the markings or in the ones I found no markings.
A couple of caveats (easiest thing to do is just to post the same post here
If your asking about San Jose built cars typically cars from that plant were not used for articles or promotions.
If general any plant (usually Dearborn) shots then yes there are some and they typically show no marks or in the ones I found different marks than you will see guys using on "restored" cars. In some cases these cars were pilot or very early cars and often had been changed (improved) for road test and such. In other examples of magazine cars and articles the cars were drag race cars that had already been modified or even had engines apart to improve their chances. Both of those types of cars are not that much use when looking for reference cars for a restoration or just research IMO
On a few, likely because Ford wanted to show off cars with a lot of options, they ahve AC so the the compressor kind of gets in the way of viewing those surfaces
Here are a few I found when looking through some of my collection. These focus where often people will apply markings to the drivers side head and valve cover face.
Couple of different 69's on upper row - bottom row a couple of different 68's
And a shot of what was likely one of the prototype 69 GT500 so possibly not a production engine nor practices shown but you asked about period pictures
Also want to remind people reading this I'm not suggesting that no 69 428 received the markings asked about in the original post just the idea that ALL were marked in that way or markings. The OP originally posted on multiple forums so we get a bit of cross talk as well as different discussions on the different sites
