With a rear that is narrowed (2" per side, in my case), is there much of an issue running stock rear discs on a 15" rim?

I only need a 15x8 wheel right now for a 10" Drag Radial. With only, say 4-1/2" backspacing (my estimate), I was wondering how much clearance work needed to be done on the caliper.

 

Your going to need a 5.5 bs.

 

Since your narrowed 2" you can get away with less backspace anyway. So you should be fine. I run a 50" 9" rear with Wilwood calipers 15x8 wheel with 4.5 inch BS. No issue at all.

The more backspace you get the deeper the caliper sits inside the wheel.

 

Have you ever done this on a F-body?

 

I maybe leading you wrong with a 8" rim.
I apologize.
You want to keep your wheels tucked in as much as possible though.