340 manifolds in a 66 cuda?

I have been told they will & they won't (no idea at all about the PS). I have some pics of a 66 with early 340 (the expensive ones) manifolds on it. They're in there. One of the members here said that he had a set on an early A but that he could only fit small pipes up to them because of tight clearances (maybe 2 1/4"? I can't remember for sure). I have a set & maybe I'll get off my a$$ & try them in there one day but I've been going nowhere fast lately.