IIRC all sbms prior to 1970 were red.
But paint is cheap. I first painted my Eddie headed 367-beast red when I dropped it into my 68 Barracuda.
Never failed at car shows; " oh a 273 how cute!"
Yeah, those numbers code out to a 318 block on the side of the block in the pics. You can make them out barely but believe that's what I have is a 318 with some headers on it.