Should I change gears or not?

It’s a ‘72 Duster mild 360/727 (stalls about 2600) with 8 3/4 rear. It’s open right now, but I have a sure grip to install which is why I’m asking if I should change while I’m in there.
It is a street car. It has no mini tubs, but I do have the kit to move the springs in when I get the chance.

I have a set of 28x12.50/15 M&H cheater slicks on some weld knock offs. I put them on last night and they clear everything, but have maybe 1/16th of an inch gap between the sidewall and the springs.

I just don’t know which size rear tire to go with.