My plan for new wheels, what do you think?

275’s aren’t supposed to be mounted on anything less than an 8” wide rim. And on an 8” wide rim they’ll touch the springs and the quarters at the same time with the springs in the stock locations.

Not only that, but you’d be deforming the tread, which will effect tire wear too. And you won’t have any more tread on the ground. Better off putting 245’s on 7” rims and operating within all the manufacturers specs. Even those are tight on some cars, not everyone pulls off 255’s without rubbing. The Valiant model helps some because of the higher wheel openings in the back, but unless you want to get out the hammers for the quarter lip I’d stay away from anything wider than a 255.