Mantra gulwing tunnel with 468 bbc, duel carboretors

Hey, I just recently bought this jet boat with a 468 bbc, it has a weind duel carburetor manifold with holley 9776 450cfm's on it, I'm told it's putting out between 500 and 550 hp, I have heard lately that those are not very good carbs and I want to change them, so I'm hoping someone can suggest a good carburetor setup and also do i need to use an electric fuel pump or will a mechanical one will work. It has an electric one now but it only putting out 5 lbs of pressure