I guess in a pinch it will work ok, but chances are the tank is rusting from the inside out and it won't be long before it starts leaking again. I would just find another tank and replace it.
I was afraid of that. I just wheeled the truck a few weeks ago for the first time (since I bought it, and probably the first time in years), and sloshing around a full tank of new gas probably stirred up some crud on the bottom of the tank.
Any ideas where to get a brand new tank?