Override Tranny (I can hook you up on that), lockup clutch, longer arm, stiffer shock (Marvin or strut)
And then the lighter stuff, drag axle, light weight rims/tires, A or J arms, Tie rods, steering stems.
If it's gonna be strict drag bike, out of frame pipes. If he's gonna play in the dunes here and there, get inframe pipes.
If he's gonna go 7, have him go 10 mil. There is no reason to build a 7 mil bike when a 10 is the same price.
I can hook you up with a cheap 10 mil crank, NEW as well....price depends on what bearings you want to run on it.
Snop, here's a new site with the ATV drag racers in mind as well...you and him take a look around.
http://www.atvdragracers.com/