Iron heads?  The cam and compression need to work together.  The more duration (the later the intake valve closes), the more static compression you will need in order to build cylinder pressure.

What type of boat and its intended application?  What impeller (could change)?  What type of exhaust?  Wet or dry?

Hey guys so i got a 460 torn down and very new to this rebuild thing.. what i know it has
 40 over piston,
claysmith cam h 290 8 b
750 holley carb
Pertronix ign
D3ve a2 heads

So my block is at machine shop with heads finding cc on heads and getting block bored 60 over. My question is what pistons and cam would b good to keep it on pump gas but still runs strong any help would be great dont want to dump money and b disapointed

The common 1973-up 460 comes from the factory with a real world compression ratio of just 7.8:1. Swapping out pistons to gain compression is a good bet. For a mild budget build, deck the block to 10.295" and use a Keith Black Silvolite 3109 piston. They are for the 1988-1992 460 FI engines have a very shallow (7cc) dish.  With the bore increase, the block decking, and the 3109 pistons, your compression ratio will increase to about 9.6:1

Pocket porting (ie, bowl blending) of the D3VE heads will also help measurably.