I had good luck using a DT200R rear wheel, caliper and mount plus the dt200R brake line. All lined up really well only had to machine down the TT sprocket side spacer by a few mm (not sure how much now been a while). Welded an extension off the back of the existing brake pedal and mounted a YZ426/450 11mm rear master cylinder off the back of the subframe rail (conventional location). The TT sprocket bolts straight up. You will have to shorten the drum brake locating stud (shaft?, sticky outy thing?) but the whole setup could be easily retrofitted back to drum rear brake if required.
This setup has worked quite well for me after mucking about with various master cylinders i now have good pedal feel and travel.
Pictures would help i know but i am working away from home and will not be back until next week, i also have no idea how to put photo's up now that PB has gone.
PM me with a number later in the week and i will txt you some photo's when i am home