I don't see why that would make a proprietary master cylinder for the Trail Boss. SO I agree that its quite probable another model will fit and do the job.
If that doesn't work, I have had very good luck with Babbitt's. http://www.babbittsonline.com/
2015 RZR 900 Trail BLK. Pearl
2007 Polaris Sportsman 700 EFI SOLD
Running 26" Maxxis Big Horns on Crusher Black alloy rims, 1.25'' Spacers, EPI clutch kit W/spring mods, HD springs F&R, Moose front/Ricochet rear CV guards, Moose tank bag, Polaris rack extensions, Lock-N-Ride lo & hi windshields, Acerbis hand guards, CUSTOM mirrors & mounts . A 3000# Gorilla winch, W/Am-Steel blue synthetic line, running thru a winch saver and an aluminum fairleed. Thor's foot pegs and CUSTOM rear rack support frame. L&R WES seat box W/LED light & internal 12V plug. L&R Sportsman Box W/ internal multi 12V and USB plugs. CUSTOM front and rear mud flaps, CUSTOM dual side mounted 1.5 Gal Kolpin gas cans, Modified stock muffler with a rear exit & 800 air box lid W/UNI air filter, for better flow in & out.
CALL Thor @ www.TheATVSuperStore.com
Check out my ATV videos and please subscribe!! https://www.youtube.com/user/cwlongshot
I PROUDLY SUPPORT OUR TROOPS!!