X2 on ditching Team G, it's definelty holding you back.
I run a dart single plane on my BBC 496 with good results but a Vic jr is a good choice too.
Did you change the jetting on the carb?
More compression should warrant more fuel, I'd go up at least 2 jet sizes for starters.
What is your total timing?
Mine likes 40 with 110/112 leaded race gas any lower than that and it's a pig.
Your heads sound plenty big, your cam could be holding you back some too.
Another thing is your convertor could be too loose fro your new combo, just food for thought.
Goodluck, Cp