I mocked up the front end with the caliper last night. I had to order some oddball wheel bearings to make the tri z hub work with the 17mm bw200 axle. I will also have to turn up some top hat style split bushings to adapt the bw axle to the rmz forks. I had a spare dr650 caliper laying around, which is the same caliper they use on the rmz450 (or so ive read) I think it will play nicely with the triz front wheel. There isn't a bunch of extra space, but as we used to say in the machining world, "clearance is clearance". If, once everything is solid mounted it ends up being to close for comfort, there is plenty of meat on the caliper to grind and shave it down for a bit of extra room. I will also have to make an adapter place to bolt in a 250mm rmz450 front rotor, which should be simple enough since the bolt circle for the tri z rotor is fairly small.
It is always a game of "one step at a time" to reverse engineer this stuff. I don't tend to draw up or design the whole project from start to finish which gives me a bit of freedom on the build. In this case I have to first set up the axle so that i can get an accurate measurement of fork center to center. Then I can draw up and fabricate the triple trees. Only then can I put the front end on the bike, which will allow me to work out the swingarm design and rear suspension to match the front. All part of the fun.