I'm looking to getting a pair of buckets off a '72 Cutlass but I want to recover them using '69 Chevelle covers to match my rear seat. Will it be a problem?

same seats different covers and foam

I know the seats, brackets, etc are the same. So I take it because the foam is shaped diferently, the covers I want won't fit properly. Right?

Order the foam and covers you need/want for the particular year. The frames are the same. I sold my buckets to a guy with a GTO resto shop.