Hedmans are OK. Not the best quality - nor are they the worst. I have a set of their shorties on my fastback.
As Shaun said, Hooker SCs are very nice and probably higher quality than the Hedmans. You do pay for the difference in quality, though. Hedmans can be purchased for as little as $110, Hookers are about twice that, IIRC.
A lot of folks here swear by the no-name Tri-Ys many of the large vendors sell. As I understand it, ground clearance is better with that design than with many full-length headers. They can be purchased very inexpensively ($170, IIRC).
Whichever brand you choose, buy the ceramic coated model (or have them coated), otherwise keeping the darn things painted will be a constant struggle.
The super comp's fit is excellent,but they hang rather low.My car was lowered two inches before I switched to the super comp's,and I had to raise it back up one inch to keep the collectors from dragging.I'm considering switching to the FPA tri-y.According to the research I've done,they make more torque than the super comp,and only give up a little high rpm horsepower,and fit much closer to the floor than the super comp's.Anyone out there running the FPA's?
I have FlowTech cermaic coated headers on my '66, JBA shorties on my son's '65, and an unkown full length headers on my daughter's '69.
I've been very happy with my FlowTechs, but they don't provide much in ground clearance. My car is lowered 1" in front and I have 2 3/4" clearance from the collectors to the ground. Speed bumps are a challenge, but I'll live with it, since it's tough to get a tight fitting header to work with the AOD.