my 69 has a rear strut relocation bar welded in the rear and my struts have been moved to the inside of the frame rails rather than strait up and down inside the wheel well....is anyone familiar with this set up and if so, how wide of a wheel can in go with it...i do not want to mini-tub but want a deep dish look. i have a set of 15x8 rallys with about 3-3 1/2 backspace.

That is a common set-up (available from numerous aftermarket manufactures) used to move the shocks out of the way of larger tires.

As far as 'what fits' - only you can decide that on your vehicle.
You need to take into consideration many points;
* ride height
* suspension travel
* fender lip mod
* rear axle location
* rim dia
* rim offset
* tire dia
* tire ratio

Once you mix and match the above you'll find what the max size(s) that will work with your vehicle.

Best site resource is the "Wheel & Tires" forum - http://www.camaros.net/forums/forumdisplay.php?f=17
Read through the various 'Stickies' and posts for combo's that match your set-up and go from there.