I got some kind of Yamaha pegs for my Trident, quite a while ago so I don't remember which Yamaha anymore. They looked exactly like the Triumph pegs, except that they were drilled for an 8mm-ish mount instead of the 10mm Triumph mount. 5 minutes with my power drill made them fit.
I think I had Buell pegs on it at the end; those required machining as they were too wide to fit into the mounts.
Cheers,
-Kit