Well....
I have not road raced (officially) but I do want to set up a car like this someday
It seems to me that the rear should be set up something like this
1 Very flat and thick springs unlike Super Stock set. More like what a late '70s Trans Am would have
2 You probably want to have them as far apart as possible so the stock location is fine
3 beef up the spring hangers and shackles as well as the mounting points
4 I think you have to play around with the shocks to get them right so ajustable would be a must
5 Big effen swaybar and links
As for tire size and wheel offset you might be pushing it a little close. The rear springs are in the
car diagonally at a 1.67 degrees so you have more room at the front of the wheelwell then the
back. I don't think much more then 4 inch total offset would work so the outside of the tire
gets real close to the wheelwell lip, you might need to trim alittle on that lip
This guy seems to have alot of these problems worked out on his A-body so take alook at his site
http://hometown.aol.com/pwall5/cars/2cudapag.htmlHe seems to have his act together