Check out how the cross member was modified, there's both good ways and bad ways if you know what I'm saying.
Big blocks fit with some persuasion and make an excellent mod.
The 396 in my 72 K/20 looks great/stock but has very short vale covers on it to clear the firewall.
I'd be S.O.L. if I wanted to go to roller rockers that needed a taller cover...
