Who makes a replacement intake for a stock 500 HP?
Dart single plane rectangle port 4150 9.8 deck??
guess I will have to drill the PCV hole?

dart makes the manifold for merc,fixx knows the part number,im sure he will chime in sooner or later.

unless you can find a clean oe one then tes you will have to buy a dart one and you will have to drill and tap the pcv hole and drill the intake for the pcv ...you can ask dart to do it for you for a fee..your intake is a dart with the dart ground off the intake,if you look close you can see where they ground it.#41114000GM is the replacement..make sure its not a bull dog engine,that one is a diff manifold