I'm guessing it is referring to a 'red cent', a term for a penny. It's rarely used these days, but one might say "I wouldn't give one red cent to have his job". This means that I really don't want his job. "How much would you give me for this drawing?" "Not one red cent." So to say 'as long as he had a red' would be saying 'as long as he had any money at all on him.' Anyway, that's my educated guess.