ON my '91, I am running 35x12.50's on 15xz10's w/2.5" BS and a suspension lift of 2" 4Crawler BL, 1.5" BJ Spacers, 2" cut out of the fenders, and the use of a BFH to the body seam and fire wall. The track width is 73"(tread shoulder to tread shoulder. There is just a little rubbing at full lock under full compression, but not enough to damage the tires or the body.

Here is a shot from above holding the steering wheel at full lock:


Here is one from the side turning at almost full lock(turn to full lock and letting go of steering wheel):


Since the tires just barely rub now w/any lift, you should be able run 15x6"-15x8" rims w/2" BS and not have any clearance issues. I would start with the BL and the rims you currently have and go from there. It is unlikely that the BJ spacer will give you enough clearance by itself, even w/inner fender mods.