Thanks for all the replies and valuable info. I saw the bike today and the rust was pretty bad inside the tank! Carbs were pretty creamed with rust as well, he will do the cleaning for cheap since he already has them on the bench. As for the tank, it really needs some tender loving care to get it right. He says that he will take it to an expert shop that will completely de-rust and coat it but its expensive, about $250USD. I told him to hold off on it as I am considering doing it myself.

If it were you, would you de-rust and coat it yourself or take it to the pros? Mind you I haven't done it before. Not sure on this one...