I'd sandblast it at about 30 to 40 PSI then prep it before painting with Bulldog. Base/clear should do just fine. Flexibility additive might be a good idea too.
If ya have a minor knowledge of painting, base clear and add flexing agent the paint cant cost more than 60-70 bucks........prep is everything.........buy a cheap base that matches and buy good clear ppg is my choice... Even if ya use a flexing agent it only lasts a couple of weeks before it loses its properties....So with that said if you are going to paint it and let it sit before you put it on dont waste yor money....pm me if ya have any questiones.......
