GM A-Body IRS

[DETON8R]

Check out these links, a bit of info, not real in depth, but a good starting point for research.

http://www.rodandcustommagazine.com/...n/viewall.html

http://www.hotrod.com/howto/hrdp_071...s/viewall.html

Did you consider a C4 Vette Rear end type of set up? The gear case / center section is braced with a torque arm (like a 3-link) and the wheels are set up like a 4-link. Yeah a real oversimplification, but I've heard that most mods that narrow the set up still retain good geometry with a hub to hub measurement as narrow as 58 inches .

These guys do a C4 Vette suspension on 50's trucks and tri-fives
www.hotrodjim.com/trifive_c4_grand_coil.php

And there are a few other shops that do custom C4 Vette set ups. They mostly cater to Corvettes only but some have done other projects.
http://uscorvetteconversions.com/

http://www.progressiveautomotive.com/

And one of the guys in our club has a 69 Camaro with a BMW 7 series IRS. He liked it because it had the huge brakes, and the right hub to hub for his project. He went with cantilever shocks in the trunk. Quite a project but it looks sick, and it handles great.
http://pacificfab.net/barry-camaro.htm