Another (will this fit?) Wheel and Tire ?

Okay, then apparently you have some sort of disc conversion with bbp on the front, which might have moved the wheel mount face outward. So, we couldn't tell you what would fit.
On the back, we don't know if it's a 7 1/4 (highly unlikely with a bbp) or an 8 1/4 swap, or a a-body 8 3/4 with a pattern change on stock drums and axles, or an a- body with b-body brakes and axles, or a b-body axle swap, or which b-body swap.
Long way of saying, your gonna have to do your own actual measurements
For what it's worth, if the wheels you want are one piece and don't offer different b.s. , I would go smaller by an inch on both ends, 15x6 and 15x7.
First thing I would do is measure the actual drum to drum width of your rear (the cars, not yours), and go from there.