Stock suspension racers

I am in the process of building my 72 swinger and since I bought the car my plans have had to change from a back halfed car to stock suspension due to my budget. Originally I bought a set of cragar super tricks 15 x 4 and 15 x 12s (for sale too now) now I have a set of stock steels that I'm gonna run. I plan on frame connectors and maybe a 4 pt cage max with pretty much stock 440 727 and hopefully 8 3/4 but now I believe I have a 7 1/4 rear with sbp. What would be the max tire size I can run on the rear and any other tips and tricks would be helpful. Oh and I'm thinking bout trying to build my own set of caltracs for the rear.
Thanks
Brad