It's an RS with the Z/28 RPO added. The P/O used all correct NOS Z/28 parts when he converted it back in the 80's. I probably have the GM receipts for the brake upgrades and will either look them up or will get you the caliper numbers with some pictures of the mods when I pull the front wheels to do the brakes in the next few days.
I'll measure the backspace as well for you but think it has 7's on the front and 8's on the rear. Again, I'll confirm in a couple days when I'm finished installing the new motor for it. Been thrashing on it for 5/6 days now and tomorrow the engine and transmission are finally going back in.
