Offset spring hangers and shackles....

What body style A-body? I assume you’re talking about the 3/4” or 1/2” offset hangers/shackles and not a full 3” relocation.

And what are you asking really? Do you want to know if there’s enough clearance for those tires? Are you concerned about suspension geometry? How it changes spring rate requirements?

I use 1/2” offset hangers on my Duster, I run 295/35/18’s. Not drag racing, but there’s no reason I couldn’t. Tire clearance requirements for drag racing are less than what’s needed for the street. Narrowing the spring spacing does change the forces acting on the springs a little (longer moment arm from the center of the tire patch to the spring), but with just an offset that effect is pretty minimal. With a full relocation it’s a little more significant, but that’s just a spring rate and shock length/dampening adjustment.

And you don’t want to run 275/60/15’s on a 10” wheel anyway. The recommended rim width is 7.5” to 9.5”, and the “measuring wheel” is a 15x8”.