Re: 15x10 backspace 69 ?
When mine had stock wheel wells and stock rear end I ran 15X10's with 4-3/4" back space and 275/50 tires or 28X10" slicks. If you used these rims you might need to use spacers to keep the tires from rubbing on the inside of the wheel wells.
Here are some old pics with this set up.
'69 Camaro - 429 SBC Dart Iron Eagle 9.325" block, Crower crank, Crower 6" billet rods, Ross pistons (10:1), Total Seal rings, AFR 245 heads, T&D steel body shaft rockers, Cloyes Timing set, custom ground 4-7 swap solid roller 274/286 @ .050" with .704" lift, Dart single plane, Holley Dominator EFI on E85, Injector Dynamics ID2000 Injectors, Stef's #1705R oil pan, F2 Procharger, Lemons 2" primary 4" collector, ATI 9" blower converter