Be darn sure the Pulse Hole on the carb lines up and no leaks around it. Since you flipped the carb. Had the same issue happen to me but on a Fuji Engine.
If all is correct-Sounds like you have to adjust needles-High end first, then low. It may need to be open bore than normal or just the opposite. Very tricky when larger carbs are used. Is the Venturi size #28 ??