PRS is upto 65 on the pinions now - we ran a 76 spur w/ a 65 pinion on the 21.5 motor on the VELODROME last weekend (It was too tall, we ended up back down to a 62 pinion)
I have a few HUGE 48 tooth pinions that are quite old...they were made by DELTA...found them a couple years ago at a HobbyTown USA in AZ (I think they are 50 and 51 tooth)