I hear many people use Ducati single's and honda VFR 750 < it's not exactly bolt on, but it should'nt be the worst thing to fit the b12 or the b6, im going to try this my self in a couple of months, so if anyone know someone that have done this, i'd really like to talk to them... just to know just how much work and time it took...
Ducati and VFR swinarms could be found on ebay for a reasonable price, and you get the 5,5" or 6" rim too, which is pretty neat...
I live in norway and i got an offer on a VFR 750 swingarm with all parts, wheel, brake, + + for 6000 NOK, = 400$ i think...