1972 Dodge Colt

I really don't want to guess, but it seems that way.
It's just hard to believe 2 little 1/4-20 studs and nuts could cause that much problem.
Talking about an 80 lbs head bolted to a big cast iron block.
I agree, but if you are certain that there is no interference with the valve cover, I can't think of anything else it could be.