I have an unusual situation... as would be my norm

Concerning my '59 3200 project, I have two 261's.
The first was rusty all over so I was starting from scratch. I rebuilt it and researched paint color for it.
I found online, yellow or green was the correct color.
I bought the Detroit Diesel Alpine Green paint and finished it up. It looks great!
OK now for the twist. A '58 1/2 ton truck that I bought for parts from a work buddy had a 261 in it. His grandfather bought the truck new from a local dealership and the engine has never been rebuilt... until I rebuilt it. This engine was like new! Everything was standard size and there wasn't even a ridge in the cylinders... all I had to do was hone them.
This engine was definitely Blue... after the rebuild, I repainted it the same, Chevy Engine Blue.
First off, I would never have expected a 261 to be in that truck. second, the engine color isn't what the net says... oh and one other thing... the "stamping" code on the machined pad near the distributor? There isn't one... the pad is clean.
I don't mean to hi-jack this thread, I just thought I'd state something different concerning the topic. Maybe engine color wasn't a spec adhered to?

Thoughts?
Jerry