Back Spacing, which way?

Aw crap, now I see you want to use a 7" wheel. So, here is my revised advice: so you want to move the tire in about 1/2" to center the tire in the space available, so your new backspacing should be around 4 3/4" with the 7" wheel. That is equal to a positive "offset" of 3/4" with the 7" wheel.

Don't forget, for measuring backspacing the 7" wheel is actually 8" lip-to-lip. Nearly every wheel made is 1" wider lip-to-lip than the wheel's bead width (7" here).