Yeah I've had a look at that. Also found a site where it cross references everything for you based on make/model.
Here are my options:
Cheapest: content myself with a single front disk, rebuild the caliper and get new brake lines. I can buy a fork brace for these sliders for $100.
More $$: try to find the entire front end, or at least the rotors, calipers, and sliders, from an XJ750. I'm not 100% sure if the 650 fork brace will work on these (it should), but I may need to build my own brace. I'd also need to buy a new master cylinder (xj750 mc won't work because of the drag bars)
Most $$$: swap the entire front end for one off an R6. It's going to be real tough to find a decent price, and when you figure in a couple/few hundred for new bearings and machine work, this would probably be way more money than I'm willing to put into this bike.
My front brake isn't as firm and powerful as I'd like, but upon consideration, it's probably best to just stick with the single front brake. Rebuilding the caliper and replacing the old lines with new braided ones will hopefully tighten the brakes up, and if the single disk was good enough for the bike stock, it should be good enough now that the bike is significantly lighter.
Founding member of the Leave-Me-Alone-atarian party of Canada.