The reason we keep asking about the clutches, is most bogs are clutch related!
I know we are talking about a Vintage sled, but the same things apply! Start by cleaning the surfaces with a scotch bright or sand paper, then blow them out reall good! Then measure the centers with a tape mesure! Next take a carpenters square and go across the spark plugs to the driven clutch!If anything you want the engine to be just forword of center on the clutch side, so that under load it is square!