74 Duster 4 banger Street/Strip Build

OK, so I need to get my tire diameter sorted out. I'm thinking I'm gonna make room for 12.5 wide or so, but run a 10.5 (small tire). What diameter do you guys think I should shoot for?
275/60/15 (28"x11.50)

Here is my Demon - uncut 68-70 B body 8 3/4, 275/60, factory 15x7's (3.25"bs or so)

I plan to run a 15x8 or 9" w/ 5.5"bs Weld Prostar, and a Nitto 275/60 drag radial - going to likely have to roll the outer lip, and beat the inner in a little but has tons of room inside currently (over 3" from tire to wheel well)