i have used the POR15 system and it worked very well. it is not a big job. just make sure, that you follow the instructions 100% because there is not only a thin layer of rust, there is also a thin layer of oil (from the gas) in your tank and POR15 hates oil.

http://img24.imageshack.us/i/tanktg.jpg/


'59 Apache
'67 Mustang