I have tried Mac's, Pacesetters, LS6's, and the custom 1 3/4" block huggers. The only fit is the block huggers. I believe that long tube or mid length headers could be made, but nothing that is out there now will fit, except the customs. I bought 10' of the flexible 1 3/4" exhaust pipe to see if I could sort out a design. Maybe when the car runs I'll get the urge.
Edit:
Here's a link from when I was trying to fit the Mac's.
http://forums.hybridz.org/showthread.php?t=97147