Send the tank in my coupe to Gas Tank Renew because I’m tired of rust? Not for $650 plus shipping costs both ways. Sheesh!
I’ll steal one and go to prison for it before I pay that. It’s become a do-it-myself project. 
I did a tank for an Allis-Chalmers tractor I restored 30 years ago, using Bill Hirsch’s product, and it’s still good today.
I was quoted $450 for an oval tank that had some rust but was otherwise sound. Tried to buy a new one as they are advertised for $150 in the venders catalogues but none are available as I understand no one is making them anymore and the existing supply is exhausted. The people at Snyder’s said they are trying to get someone to start making tanks again for them but had no idea as to when that might be.
I have restored 4 different gas tanks over the few decades: two WW2 jeep tanks and two model T gas tanks. I have used KBS coatings for each and have had no leaks at all. There are different methods of getting rid of heavy rust: electrolysis, acid etching, or simply using Apple Cider vinegar. After using one of these, I follow the KBS coating system for gas tanks. They have a three step system: clean, blast, and seal. I haven’t used other products that are on the market, but I’d recommend this one; costs about $50. Takes time but worth it. Good luck.
John
I have had gas tanks cleaned at radiator shops. Never any issue afterwards.
Maybe 25 years ago I got a gas tank sealing kit from Bill Hirsch. Followed the directions and used it to coat the inside of a new 1967 Mustang gas tank. Let it dry for a week.
It was fine for a couple months then all the coating turned loose inside the tank. Clogged the fuel pump and lines and carburetor real good. Not a fan.
The one I did 30 years ago is hanging in there.
The question I have is how to prevent the sealer from blockingvthe fuel outlet on the 1926 tank. It’s not as straightforward as screwing a plug in then removing it after the sealer cures.
I will say tgat the chemical I am using is doing a great job removing the rust. Metal Rescue rust remover bath concentrate; got itvat Advance Auto Parts. Looks like water, no smell, no burns, each bottle makes a gallon of cleaner. Not cheap at $20 a bottle.
It’s unlikely to rust in your lifetime. If the rust is gone than put the tank in and forget about it.