Hooker 6114's fit well. The problem with these headers is that they really dent tubes #1 and #2 to make room for one bolt each on the rear side of the port.
The FPA headers had a few areas of interference. On one block a tube hit the bottom edge of the block on the driver's side. I had to relieve the block a bit but these headers cleared a different block in the car now:
Another area was the upper idler arm bolt. I just used a shorter grade 8 bolt. Some just cut the original bolt or use more washers under the head of the bolt:
One more area that is close is the passenger's side motor mount. It didn't hit in my case but I think others had problems with this:
Not too close on the driver's side mount:
No problems clearing a C4:
If your engine is already installed, just take off the 2 motor mount bolts and jack up the engine so it rotates away from the side you're working on. Turn the wheel so the pitman arm is out of the way on the driver's side and take the idler arm off on the passenger's side. Jack the car up and install from the bottom.