Recoil,
When you build a custom like you have, you are the only one who will know what is what. A tank might be spendy. If the one you have is still working, you can spend the money...but like a lot of parts on an old or custom truck, you pull the part, either post a picture of the tank and sending unit on this website or bring it to your local salvage or auto parts store and have someone ID it...then go buy a new one...
Example...I wanted a paper air cleaner element instead of the stock oil based cleaner...I pulled the element out and went to the auto parts store...20 minutes and 6 or 7 boxes later, I came up with the correct paper filter...I know a $12 air filter is a lot different than a gas tank....but if you post a shot of it....I would guess someone on here knows what it is from...It is almost scary what you can find out on here...
If the quality and appearance match what you are trying to do....leave the tank as is. You will have other stuff you will want to spend your money on....
Just my opinion......
