rust issue

[REDROCKER652002]

Not sure what I am asking, but gonna try. My son's 69 is showing some rust on the cab top. He loves the rat rod look and does not want to do much to get it painted. I am good with that, I think it is kinda cool too. But, I want to try and save him some trouble later on by trying to stop the rust. I have read and saw a you tube video by eastwood about rust inhibitor and how it can be used and not need anything over it. My thought is, if he can spend a weekend doing this, and save his Rat Rod look, would it be worth it? I am ok with getting a DA and just hitting the spots with sandpaper and primer, but he loves the look of the truck and I don't want to discourage him by putting my two cents into it. Any advice out there would be nice. RR