Try peeking in the plug holes with an inspection light. The sharp side of the piston intake deflectors should be pointed towards the intake ports, which are on the right side of the engine. The left side of the powerhead has the flat cover with many screws, this is the exhaust side of the powerhead.
So, I am assuming you never ran the engine prior to rebuilding because it was seized. Has the engine always run this way since the rebuild?
