I did alot of research trying to find a good header for my 72 Mach1 with a 351C4V 4speed car and decided when I get a header it is going to be the ford power train ones. #2 on my list was Hooker Super Competiton. I think the Ford Powertrain ones will have better ground clearance though. I talk to thier desingers about the header and found out they acuatlly took 3d models of Ford car and checked clearance on the computer when designing them to make the best possible header. Exspensive but my #1 choice. Only thing that may cause a problem is your Z bar. There are two different Zbars that ford put on mustangs; one works and one causes problems. Ask them which Zbar is the one that works.
Hooker Supercomps will not work with 351C 4v PS 4 spd. I had hard contact in 5 places. I went with the Ford Powertrain headers and they fit very nice. You will still need to make a simple change to your Z bar but that far outweights the Hooker alternative. Stan will talk you through it. You will also gain about 5 inches of ground clearence. The Hookers will hit every speed bump.
If you still want the hookers I can sell you a ceramic coated set that after a week of beating almost fit........Never run.. /forums/images/icons/smile.gif
Sanderson shorties. Best headers I have ever seen for this appilcation and only required a little modification to "Z" bar. No problems with dragging the ground or anything like that. Check them out, I am very satisfied with mine.