I have not heard of any member successfully put other calipers, etc. on an R65 .
A few have tried, but I have not heard anything about a completed conversion .
Getting there!
I have amassed:-
A pair of matching disc rotors
A pair of Brembo 4-spot calipers from a K-bike
A 17mm Master cylinder kit.
Still to do.
Measure up and have machined a pair of stepped adapters to mount the calipers.
Sleeve my old 13mm master cylinder to 17mm and buy it a new reservoir
Have braided hoses made up.
Confession time.
Since I fitted a braided line to my single caliper F08 I am less enthusiastic about fitting the 4-spots to the R65. In fact, I've pretty much lost interest.
Of the gear I've accumulated, the genuine serviceable rotors would look nice on the R100 and the calipers are good spares to keep for my K-Bike project.
In fact I'd have to say that a stock system in good order, with perhaps the addition of braided lines (In my case I specified a braided line that has a black "rubber" outer cover so that it looks stock) works perfectly well and you would really have to have a serious need to go to more exotic brakes.