I don't know the Yamaha part # for the r/r, but an ideal R/R for the Vmax is Shindiguen(?) part # FH010BA
Shin makes r/r's for pretty much every bike on the planet. This one is for a Kawi ZX10/ZX14.
It's considerably thinner/smaller than the R1 part(no need to cut down the fins), and it's been working great for me for over a year now. Mine lives bolted to the rear coil mounting plate, since I run COPs. It's thin enough that the seat fits fine, so it's thinner than the coils that were originally designed to be there.
Retail from a dealer they're expensive, well over $100....I got the one above off ebay for $20.
See my sticky in the "How to" section about the charging system for more info.
If you're really in a rush you can make a r/r out of parts from radioshack....made one for my 2-phase B&S motor when the original died that's been working good for a while now, though all it does it power one 30w headlight and charge the battery.