A lot of lower width wheels like 15x6.5 and 15.7 are pricey these days and the ones that are decently prices are 15x8s, im also standing on stock suspension so idk if it will cause scraping, and will it also change handing the same way or its gonna add more weigh than steelies.

(Image wont load but im thinking of getting Sparco FF-1 wheels)

 

15x8 +20 for sure are not a proper fit for the car.. really depends on what you are going for. The wheels most likely will stick out past the fenders and will rub if lowered or weight added to the car. Either way they will "fit" the car but not correctly. A 15x7 +35 is probably the max you should go if you are wanting something that will not rub on stock height or lowered.. even the +35 is pushing the limits imo.

 

im on stock suspension so no coils or lowering springs

 

j's racing used 16x8+42 up front and 16x7+42 rear. but you could prolly get away with 8's out back too. i think theirs was lowered as well.
also, I love your wheel choice.

at +20, youd experience scrubbing when turning.