Welcome , 6' 200lbs dunkers FTW!

Looks like you are damn strong , 420squat@205bw is 2,05 strength/bw ratio. And you said u squatted them for reps , so its even higher.
That relative strength is BEAST, I think that you could get to 40'' just getting used to jumping using your new (huge) strength , i expect you to get there pretty easy and soon! Also , comfortable one-hander for 6' means something like 35 or 36 inches , so ure not that far off!
Andrew?