Mac mid length headers, 1 ¾†tube.
It looks like the headers (at least for the drivers side) will fit with a little banging on one tube and cutting the flange off then welding a 3†30 degree pipe on the end of the header. I don’t have the engine in the car yet, but measuring from John’s mounts makes me think I can do this. I know the LS6 exhaust manifolds wont fit, the Fbody ones don’t fit, and the Pacesetter’s don’t even come close. Here’s what the MAC’s look like.
I highlighted where the mount is at in the picture from the top for reference.
http://www.circuitflex.com/MacDriversSide.jpg
http://www.circuitflex.com/MacDriversTop.jpg
I’m waiting for my clutch to get here so I can get the engine in, so I’m tearing into the electrical in the engine bay.