The yamaha brakes are 130mm diameter. They can be modified to a certain degree but because they are magnesium, it makes welding on them not so easy. Im not sure if all the honda ones magnesium either. Suzukis are. I suggest hoping on ebay and loking at some photos of some brake plates. Even just buy a Yamaha one, once you have it in the flesh you will know if you can make it work or not. If its no good, dont worry guys on here are always looking for those brakes and you can re sell it on here easy. Another option is to turn a single leading brake into a twin leading by adding an extra pivot and arm. It can be done, by either changing or modifying the shoes & adding a secton piviot cam and modifying the cams. There is info on the web how to do it and i have seen it done on bikes before. Going to do it myself infact.
Also be aware there are 2 different Yamaha TLS brakes for YZ/IT. One is harder to get than the other