Yes, the piston needs to have the notch pointed toward the front of the engine. The wrist pin is offset, and a reversed piston will cause an annoying slapping noise that will eventually collapse the piston skirt. I doubt if the offset is enough to see from the bottom, however. To be safe, better pull the head and check it out. If you haven't warmed up the engine, go ahead and reuse the gasket.
Jerry
