I spent some time cleaning up the gas tank and now it looks much better. I just used the hose, some Simple Green, a wire brush, a toothbrush, and a small putty knife/paint scraper. Oh yeah, and some elbow grease.
There is a cap on the top of the tank that removes by turning counter-clockwise. The float mechanism that runs the fuel level sender is attached to the underside of this cap. My float mechanism is in excellent condition. The PO may have replaced it, or it has just aged very well. I also had an opportunity to peer inside the tank and the surfaces that I can see are pristine. Not a sign of rust and no debris. This is a very good sign and now I am thinking I won’t need to seal the inside of the tank at all.
I used more Simple Green to rinse out the inside of the tank to get it as clean as possible. It took about 30 rinses before bubbles stopped coming out, but I figure the effort is worth it. I don’t want any soap mixed in with my gas. I read that it is very important to get the inside of the tank totally dry to avoid rust. I rigged-up a hairdryer to blow air (on the “cool” setting) down through the sender-mounting hole and into the tank. It seemed to work pretty well out under the hot Texas sun. My girlfriend, however, was not pleased when she emerged from the shower unable to find her hairdryer.
Next up is to prime and paint the tank and it will look like new!