If throttle response at low rpm, clutch engagement, and street drivability are what you're really concerned with............it may not be the carb cfm, which is a little big, but more of a initial and total mech. advance issue to push on the motor with all that .050 duration and mildish 3.55 gearing.

What is your initial timing? Total? And then mech. advance is what I'm getting at?

A slow/soft advance makes many a carb seem too big.

I'd tweak the mech. advance and if you're still not happy drop down to a 750, then 700.