[72GTOMN]

Hello,
Today I picked up a 1971 Lemans sport convertible. It seems pretty original except for 1 repaint many years ago. Guy I bought it from has had it since 1988. Figured I couldn’t go wrong for the $5000 he wanted for it. I just started to look it over and it’s supposed to have a 350 2 barrel. I cleared off the engine code and it says YC which I think is supposed to be for a 455. So I’m confused. It still has s 2 bbl on it. Are all Pontiac blocks stamped with displacement on the sides somewhere?
Thanks!