The problem is probably two fold:
- your power shifter: the cam. What a cam like that does is shift the power. It taketh from the low end & giveth to the top end....which is what you are feeling.
- comp ratio. To try & claw back some of the lost low end, you need to raise the CR.
I would advance the cam at least 4* [ 8 would be better ]. This would make an improvement you would feel, but it is not a night/day difference.
Congrats on using a great carb & your tuning skills with ign timing [ plenty of initial + MVA ].