I doubt you will find any CAD drawings on Club Cobra for wheel offset. You can find plenty of discussion, if you do a search on wheel offset.
I have a Street Beasts with a Strange 9" with shocks and coil spring set-up, like a mustang. The max offset I can run with this is 4.5".
You can go to places like tirerack.com and they explain wheel offset. In a nutshell, measure from the face of your axle to the nearest thing your tire will touch (frame, shock, spring) and that's the max you can go in that direction. It really depends how wide of a tire you plan to run and how much you can stuff under the car.
Good Luck!
