Not trying to jack your thread NutNuck.... but, yes, those are stock disks, blanchard ground and lightened. They're not chromed though - just painted with JP1 Yamaha Silver and thrown in the oven for an hour on 250deg F.
The first set of pads will wear through the paint at the contact area, leaving the rest of the rotor painted at with at least a little rust resistance. Then I'll get a set of nice, sticky pads from Vintage Brake (if they don't sell out before I order them).
There are those who recommend you don't drill iron rotors, but I've seen them raced, season after season, without any problems. However, they have to be drilled by someone who knows what they're doing. Each rotor is about 1lb lighter than stock. With the alloy rim, the front wheel lost 3lbs.
I did a MkIII disk conversion for the rear brake - wouldn't do it again for the cost and hassle. Lots of different parts - and they're all expensve. Still waiting on a custom billet sprocket carrier (c'mon Fred, summer's almost over!) that will replace the cast iron unit and accepts a standard 2-piece motorcycle sprocket. Also waiting on a one-piece rear axle that uses a spacer in place of the flange on the stub-axle. In all , rear wheel will be 10+ lbs lighter than the stock drum was.
What's the rhyme, "yeah its fun, but I'd rather be done?" That's where I'm at right now.