my concern would be if there is one hole, how many more are just under the surface waiting to make an appearance. a sound fuel tank is pretty crucial.
if you can find one used that isnt destroyed itll cost you around 250$, to have it professionally painted probably another 250ish.
use it as a bargaining tool to the seller, maybe get it for 500 off n that should cover the replacement or a good chunk of it.
i suppose with the hole in the tank its not been running either, id be concerned about other issues it may have considering its been sitting without being ran long enough for a hole to have been eaten in the gas tank.
not saying thats necessarily a sure bet other things are wrong with it. i bought my 954 from a guy who owned it a few short months, he bought it from a older guy, the original owner, who rode it a few thousand miles and parked it in a storage unit for 11 years.
it needed a fuel pump, fuel pressure regulator and the obvious things: tires, oil change, battery, brake fluid flush, forks seals n oil, spark plugs.....
not a huge amount of money, but those things added up. just be aware its a strong possibility this bike could need more than just the tank looked into.
im glad the guy i bought it from was brave enough to take on buying a bike that wasnt running and fixing those things, cause i got a super clean low mileage 954 that has served me well the last 4 or 5 years, but.. personally, i wouldnt buy a bike that isnt running and in good shape.
i love a project, but there are more than enough other options on the used bike market for me to gamble.