Clutching, Gearing, Porting???

[NWT Member]

Will be running a 99 XC600 SP on ice next season. We run 100 mile and 50 mile grand prix style races.
Any suggestions on Clutching, Gearing and Porting?
I will be running LRM twin pipes with reeds and boost bottle.
I'm also looking for Xtra 10 suspension. I can pick up from Edmonton in July.

Thanks.