Send it to Pro-Tec. They weld it up and re nicasil it. I just had one of mine done. They did a great job and it wasn't much money. Half the price of a new one.
Hey DJ! They do it all. I didn't have to do anything to mine other the put it back in and go. Very nice work done to it. They even say that they put more nicasil on it then comes stock. I'm sending my rear cylinder off this winter to have it done. The thing I really like is the cylinder comes back silver on the outside. I think it looks cool instead of the black.
Below is the website address, phone/fax etc. for Millenium Technologies. They have done four GPR1200 and 1 GP800 cylinder for me so far. About $200 generally. They can even repair gouges in the aluminium underneath the nickasil coating. About 1-2 week turnaround. RIVA recommended them to me back in 2000.