Just about done installing a set of 78038 Hedman Elites on a 71 383 column shift RR. This was a favor for a buddy, and going in I was definitely a bit leery.
Had to dimple the #3 tube at the PS box and at the T-bar. Also had to dimple the tube next to the mini-starter (not sure which #).
On the other side, we had to grind the corner of the block a bit (dimpling would have worked too, but this was while the motor was out) and the collector is touching the transmission.
Had the flip the column shift linkage upside down. Still have to tweak this a bit.
Haven't installed the plug wires yet, but we'll need a couple of heat sleeves for sure. Using Accel shorty plugs, and MSD 135 deg wires FWIW.
I'm contemplating trying a set on my 70 440 4 spd Challenger. I'm sure the issues I'd have on that car would be completely different due to the taller deck height and the clutch linkage. I'm closely studying the fit on the 383 to try to anticipate the issues on the Challenger. Of course, this all assumes fit is consistent from one set of headers to the next (it isn't).
I've been spoiled by TTi's in the past, but at half the price, I'll say the Hedmans aren't bad, particularly if you've experienced some REALLY poorly fitting headers.