I'd drop it down to a 53t rear sprocket if you can. Mine is still a wheelie monster even with that small sprocket. When it comes to the 7" driven, I don't know how much of a difference that makes over the 6".
What kind of mods do you have done? Obviously if you can get a bit more rpm out of it you'll pick up some speed.
It's funny that you say that, because the only spare rear split sprocket I got is a 53t so I would be at 12t from tav jackshaft to 53 tooth rear sprocket would bring me to a 4.4 gear ratio from a 4.9 gear ratio. This would also decrease the rotating mass, because I would have cut back some links in the chain, and move to a smaller lighter sprocket.
I hit 51.5 mph off road riding (didn't really have long straights to truly test out max spe ed.
At the time of testing I had
I have a predator non hemi
27mm/25mm intake valves
22mm mikuni
upgraded spark coil
billet rod + .02"
billet flywheel
flat top piston
black mamba camshaft
aftermarket exhaust 1" to RLV muffler
I've hit 62 mph with this same set up with a centrifugal. Hopefully next test I can hit 60mph with the lower geared sprocket, and current juggernaut/7" driven setup with 4.4 gearing
Here it is swapped to the 12/53 - looks better with a smaller rear sprocket. OP these tires are also J rated for 62 mph they are aggressive off-road tires from sunf stock doodlebug sized.