The GM 3800 engine was used in all their divisions, Buick, Chevy, Olds, and Pontiac. If your Pontiac also had the 3800 then the one from the Olds will fit. (I believe the engine was actually developed by Buick but was adopted by GM for all other divisions).
Wrong answer. The Sunfire came with a 4 banger, not a V6 so I seriously doubt the swap would work.