Chris the only 1/35 scale half track kit availiable is a very old Tamiya kit. What model or type it is I am not sure, but it may be an M3.. There is some hope that a new US half track kit will be produced by Dragon but don't hold your breath as most of new kit production is German especially Tiger or panther tanks.
Cheers
Cliff
PS> sorry but I do not know anyone who may like to build one for you.