Take a look at the tank, with a flashlight, if there is significant rust it can still be saved with a fuel tank sealer.
First, if there is rust, I have done this in the past. Drop clean sand and gravel into the tank after you have removed the sending unit from the tank. Shake it for what will seem like forever, and if it doesn't seem pitted to bad, that may be where you can stop. After you remove it all from the tank.
If it is pitted, and you have removed all the sand and gravel to your satisfaction you can buy a gas tank sealer from a quality auto parts store, or from a place like Eastwood's Restoration Company.
The last thing I would do is put a fuel cell into a daily driver. Find a quality aftermarket source for a fuel tank. A couple places like OER, and Classic Industries may be able to supply you with this part, or point you in the right direction.
Or pick up a Super Chevy Magazine those have advertisements from companies that supply parts for these cars.
