Frost keep a lot of stuff but, as said, they're not cheap
think i used some sort of red-oxide based paint (from Frost) when i restored mine - can't remember what it was called, but it was American and was 'apparently' the stuff that they paint oil rigs with (!? - can't usually trust the patter that Americans print on stuff). seemed good anyway and i didn't notice any rust coming through whilst i owned it subsequently
unless it's just been restored (?), chances are it won't be 'rust-free' as they obv. rot from the inside out and there'll be all sorts going on that you can't see
also Waxoyled mine after i'd done, which was straight-forward enough
there are companies who'll waxoyl cars for you - might be worth having a look around and calling a couple for advice/quotes