If you are starving it for fuel (either by jetting or fuel supply) you can lose 1-200 HP! You basically kill the engine.

I'm not saying this is your problem, but typical 750 carbs with no PV's are jetted around 78-80's...and you have 2 carbs so think about it...it's an easy test. If nothing gets worse or better, it might be fuel supply.

Make sure you check everything else out too...I still say dyno testing is the best way to start with a new combo to get you close on tune up, and also easy way to make sure engine is healthy and happy...i.e. valve train issues is one that comes to mind.
Brian