You can go that route, most radiator shops will do a good job of cleaning.
But there is an alternative - Hirsch Automotive at www.hirschauto.com
he has a Gas Tank Sealer (Alcohol Resistant)
and you will need
Gas Tank Etch (Pint).
I have used it on several Honda 600 tanks with very good results. You can even catch Bill Hirsch on a Saturday XXX-XXX-XXXX) working in his shop in Newark NJ. I even had a tank that I did a 6 or so years back (you can get two Honda 600 tanks out of one can and bottle of etch which I did) and it has just layed around (you'll never know when a 1971 Honda Coupe gas tank might come in handy.) Back to the story, I looked down in side just to see if the stuff was holding, and it's just like it was when I finished it. The stuff is great and it seals against (Dust Rust) which lays in pockets in the tank (normally at the top of the tank) until they pop and send rust particles into the gas. It will first clog your filter and then work it's way into your carb and engine.
Thomas, if you don't seal your tank after getting it cleaned, your tank will continue to rust. Do the research, ask the questions and take action. Sealer and Etch is 27.95 if purchased seperately although Bill Hirsch had a Kit for less the last time I purchased some.
Bill