American Racing VN 507 or VN510

The ones I saw all seem to be zero offset. (Remember an aluminum wheel is measured between the beads, so a 17x7 wheel is eight inches wide, so 4" backspace is zero offset.) That should work okay on the back, but if your disc brake conversion adds any width to the track, you might need more backspace on the front.
Edit. Don't buy any wheels till you have the 8 1/4 and the disc conversion in place. You will need measurements from your car to know what will fit.