I fitted a GSXR Radial Brake M/C on my Stelvio, works very well, although I did switch to the Brembo Monobloc M4 Calipers at the same time, so part of the (huge) improvement may be down to them.
Also fitted a cheap (like less than a replacement Lever cheap) Radial Clutch M/C.
Needed some work before use, insides were dirty, even though it was brand new.
Worked OK-ish for a while, but had a few issues with it, so switched back to the original for my ride down to Lisbon and back last Month.
I think if I could find a replacement Seal for it, it would be OK.