I have the same bike and have the same question.
I actually bought a another 91-03 Tank off someone on craigslist and that guy was saying he put a tank on there from a yamaha xs but had to do a LOT of customization and said that the gas tank idea caused him so many issues (but from the pictures he showed me, it looked great).
With that said - I have my old tank for sale - Black 02 Tank with a couple dings and scraps but no rust and petcock, if you're looking.
Let me know if interested, otherwise good luck!