It would make the left side rev a little higher, but there would be noticeably less smoke on the left, and/or noticeably more on the right.
My guess would be it is not crank seals. I would think you have an issue with the carbs. Maybe you have swapped the carb bowls (they are unique), you have forgotton the balance tube, didnt synch the carb, the floats are adjusted incorrectly, there is a bad fuel valve, mains/pilots don't match etc etc.
Also, have you checked compression?