New fork suggestions and length question

A mates bike (Trek 6000 ’08) came off the back of his car yesterday and the fork is trashed (it was going for repair anyway).

I’ve suggested replacing the OEM fork with something better. Would there be any issues with increasing from the original 100mm travel to 120mm??
Any fork suggestions for general xc/all-mountian use (no DH/jumps).

Oh, and if anybody’s got something for sale then that would be good too.

Rockshox Reba, i think merlin are knocking some out cheap

I see that the Tora’s are also seen as good value for money……. any thoughts?