They John, I’ve got a similar setup to you. 69 Camaro, Heidts IRS, but I have a chassisworks front subframe. Anyway, I ordered 19x11 wheels with 15mm offset which equates to about 6.5” of backspace. I have no clearance issues. I’m also using a 325-30-19 tire.
Check out some pics of my build. I painted my whole driveline almost a candy red, engine, trans, driveshaft, and the diff housing. Came out amazing! Your doing amazing work too and it’s coming together so quickly!
https://www.pro-touring.com/threads/...d-0-Fab-Skills