Not sure how the 200x swinger fits but you can call Rebel Sprocket and have them make a rear sprocket for the 200x in a 428 pitch. If I recall a "custom" rear sprocket is resonable, like $40-50ish. You may get lucky though, we run a 400ex axle in our long travel set up and the stock trx90 sprocket bolts right on, just got to machine sprocket for the tapered bolts.
BTW, the 200x swinger will prob work out, we modded a different Honda ATC swinger on one of our other TRX90's and it worked good. Wasnt a garage project though, glad my father is a machinist...lol
Thanks to our 2013 sponsors!
Fischer Cycle Racing
FPM
Gainer Auto Body
Tekraft Ind.
TBolt USA
GOPRO