Possible used Wheel deal.

no, and no

The fronts will never fit. The max front bs is about 4.5. Oh wait; 4.5 with a 15 puts the hoops into the Upper BJ. With 18s you could go a tiny bit more if you modify the steering stops so the rubber don't rub on the S-bar at the front side or on the frame on the rear side..... but you'll never get to 6.34. And if you fabbed spacers, then the tire outboard face will be in the fender.
To fit the rears you will need some spacers between the wheels and the axle flanges.The max rear bs on a stock rear is also about 4.5. On the B-body add 1/2, and with offset spring hangers, add another 1/2; for a total of 5.5ish. Sometimes a bit more. But never 7.27