Well, if you're really tearing into the bike I'd say you should remove the fuel pump assembly, you can get a much better look at the insides of the fuel tank through that hole. And you while you have the fuel pump out of the tank you can change the fuel filter, which almost certainly hasn't been changed in the 21 year life of the bike.
If the inside surface of the fuel tank is just dirty, not rusted, you can get your hand inside through the fuel pump hole and give the inside surface a good clean with bottle-brushes and the like.
If you do remove the fuel pump assembly you should be sure to order a new replacement gasket for it, the 21 year old original gasket will be very hard (feeling more like plastic instead of rubber). People have had problems with slow-drip leaks when they've tried to reuse the old fuel pump gasket.
Is that just dirty, or pitted? Just looking at pictures, it looks to me like it could have been rusted, pitted and cleaned up before, or that could just be crud...
Any way it goes, I'm with Greg on this one. If it was my bike, I'd pull the pump and really see what I was up against.
End of thread · 3 posts recoveredWayback Machine snapshot 20 Sep 2019