The police issue 80's Caprices and the later 70's Novas had 15x8's some larger mid 80's cars did too along with the wagons. Not too uncommon to find 5 on 4 3/4 bolt pattern wheels at the u pick it yards. The question is are they straight. A few years ago I scored(thought I did) some 15x8 Chevy rallys for $6 a piece off a Monte carlo. Not a one of them was round when my son took them to work to take the tires off them.
When looking for wheels at the yards if the car has 13/16 lug nuts it is the 5x5 bolt circle, if it is the3/4 nut is is a 5x4 3/4 bolt circle. That way you can tell them a quick glance. Mark