I go 190lbs as well and run 42's up front and PDS7(stock 250SX) rear.
You can't rely on torque, you'll have to have more of a 125 approach. We may be at the limits of this motors weight capacity. I have it very close, just not happy with roll-on power under a load(trails). It's been tough though.
It is awsume for track riding though. The bike can loop out going into 5th gear on hard pack.
Here's what I've done. 42p,180m,DDKndl#3 @ sea level/FMF AOF ignition/-4oz. flywhl/FMF carb. wing(fabricated)/Moose Torque Ring. The thinnest base gasket is next and possibly a RAD valve. Eventually a 212 bore kit w/porting.
You must do the DDK and FMF ignition($100) first. Huge improvement, pulls longer and harder, I mean sick. The wing is pretty huge to, but requires machining as does the flywhl. Not sure about the Torque Ring.