I was running this past weekend and WOT was at 3480, I noticed that if I push the throttle wide open on the carb I can get to around 3750 and a little more speed. My question is 2 part:

What rpms are you guys running on longtails

Is it safe to run this many RPMs on a stock motor(20 briggs)

Your right in the range, 3750 is ok you aint gonna blow anything... im pretty sure the gov hovers right around 3600? Next thing you gotta worry about is floating the valves if you reach for higher rpms, and that don't happen until 4200-4600ish on my motor. I hang out in that 3400-3600 rpms range at wot.