I can recommend VeeTwo stuff and fortunately it appears that Brook Henry has now bought the company back from the people he made the mistake of selling it to. It looks like he's manufacturing again -see
www.veetwo.com.au. He's also on EBay - brookhenryducati - where he's got one or two gearbox items listed. Won't be cheap given the strength of the Oz dollar but might be your best option for individual parts.