Looking to buy some 15x10" for my 73 Road Runner... Can someone help me out and tell me the backspacing I'll need to shove it in and have it in the wheel well without have to jack the rear sky high?

Was looking at the Torq Thrust II's ...

https://www.summitracing.com/parts/are-vn5155165/recommendedparts

I would recommend you measure (and/or see if you can borrow a couple of used wheels) to see what fits YOUR car..

Another persons post on here took recommendations that did not work..

I have seen recommendations for the car I have and there is NO WAY the wheels/tires recommended would ever fit...

Solid advice right there, but I can add this. On a 71-2 you can run a 15x10 with 5.5 BS and a 275-60-15 + tire with no modifications.
Ron

On a 71-2 you can run a 15x10 with 5.5 BS and a 275-60-15 + tire with no modifications.

Yep, with the 5.5 bs on a 10 inch weld I was able to get a 28x12.5 M@H bias ply on as well but the 275-60-15 in nearly a no brainer if the cars never been fooled with.

The 73-74 isolated rear assembly adds a twist to the measurements especially if the rubber is degraded and has shifted...This creates sometimes drastic uneven measurements from side to side..You'll need to measure the backspace on each side,then find a happy medium to order the wheels...
Don't take anyone's guess measure what YOU have for clearance taking the tire sidewall into account...Look at the tire's cross section width compared to the 10" rim then see what you've got between the rim and the leaf spring{less clearance at the rear segment compared to the front}..

I have run 15x9 wagon wheels with 11 inch wide drag radials on my 73 with a 8.75 rear no problem Rear will need to be lifted slightly to clear on hard bends or don run rear seat passengers I did not run rubber around the springs I used a 71 rr rear end