Your build is kinda odd ball.... it's not daily we see a 468ci build using LS3 heads going into a boat.
It's plenty of guys here you can contact for a cam. Cam Motion, Martin Smallwood, Patrick G, Geoff at EPS, Brian Tooley, Ed Curtis... even Tony Mamo might spec you a cam for those heads. I would call all those guys. Tell them exactly what you are doing etc... and go with who makes you feel most comfortable.