Engine compartment looks great, I assume you pulled the engine to paint it.
Also I noticed the 90 degree filter adapter, and single plane 2 bbl intake, late 60's engine?
Believe it or not, no, the engine compartment was shot with the engine in. Driver project for a 16 year old who just wants to sport the car. I know it's a hack but I think I camoed it pretty well, don't you think?
This thing is a bone stock 72 duster, 1 owner, numbers matching across the board, build sheet and fender tag check out, not sure how to answer your question about the late 60's 318.
If you want the manifold tell me what you'll give for it. It's going to scrap in about a week.