swede have not heard from you we are trying to work out going to keywest hope your motors are working out

A hydraulic roller cam designed for the supercharged marine engine is a nice way to go. You can have the combustion chambers on the heads opened up to 130 cc and get that compression down. Use a good head gasket like the one from FelPro with the wire in the fire ring to seal those combustion chambers tight. I like to gap my top ring at .026 for that bore size so the ends don't butt from the heat. Ample fuel is a must, lines from the tank to the carb must be sized accordingly or a lean condition will occur. Get it right and you will be happy with the modifications.
Good Luck
Ed

What hydraulic roller cam would you guys recommend for the 509?

572CI or 540CI gm block w/ supercharger.