I am located in USA, Washington state and restoring a 1981 XV920RH.  I need the complete headlight assembly with brackets.  The bike I am restoring had a Vetter fairing added which replaced all the headlight hardware.  The TR1 parts should fit.  Are such available used or new?

Good luck, the whole assembly is no longer available from yamaha unless you find a dealer who has had one on his shelf for several years, most of the individual parts are available except the glass, last year, I lucked out, my local dealer had one collecting dust.
Possibly you may be able to get the glass from a Suzuki GS1100 that also had an 8" diameter headlamp,
RandyO

The 1982 Yamaha Seca 650 also used the 8" diameter round headlight and should fit.  These bikes are only slightly less rare than your 920.  The Suzuki GS1150E & ES (1983?)used a similar light.