I would think that any "custom" motorcycle place should be able to do that for you - find one local and phone them for a chat.
If not, you may get lucky with some bits of universal exhaust in the right diameter. I know you can get these for cars for linking up custom/competition exhaust systems so you may well be able to get the correct angles and bodge it all together. Try somewhere like
http://www.demon-tweeks.co.uk/ ?