The best results usually come from:

Bowman Ring

Exhaust timing 150 degrees.

Matching the transfer ports between the case and the cylinder.

Opening up the stock muffler. In your case I'd braze a 3/4" tube in place of the existing out let.

A Carb. with 2 mixture screws. 3 or 4 MM bigger at the most. A smaller Carb. will cost you a few RPM but will transition better

Transfer ports are usually pretty good. You might try to square them up, I don't suggest raising them.

Remember more is not always better.