Custom cut gears have been made before; but like rick said there is no need, unless you want to go over 50. Talk to Rick, you guys are both in MO and he knows what's up with the honda's.
On a side note, I copied Ricks 19mm intake adapter, paired it with a 19 PHBG knock off, a malossi kit, boysen reeds, and a knock off circuit pipe on an NU and it hits 50+ no problem.