Sounds like to me your carb is way on the rich side, you think it picks up now with that jetting in the heat then wait till it cools off this fall and it will pick up big numbers.
You'll get much more consistency with a carb on the lean side in bracket racing than with a fat carb.
I would go at least 2 jets sizes down on both ends of the carb for starters, read the plugs and go more if you can, but be careful not to go to far and make sure you dont get carried away with total timing, somewhere around 37 to 38 is where you'll want to be.
Goodluck, Charles