biggest tire that can fit in minitubbed a-body?

Hey guys thanks for all the advice...as far springs im not going to be running ss springs....im going to add a leaf to my rear springs, and im keeping my /6 bars even with the 340 in. I dont plan on trimming the front wheel opening, so i think im going to move my rearend back about 1-1.5" and go from there...its good to see everybody's combo and perspective on how it should be done....really helps to know what works for others....if anybody else has any input please share

thanks Matthew