What type of engine did the 1970 and 1971 Oldsmobile Cutlass have?

I am looking at buying a 1970 or 1971 oldsmobile cutlass and the current owner says that it has a 350 buick engine in it. I would like to know if that is the correct engine for this make of car.|||I'm sure the 350 was an optional engine for that car|||Yes, but it is an Old's engine, not a Chev.