A cam with that much duration and overlap would work better with a true header. And like US1 Fountain said, make sure the water is being introduced way down stream. There have been a lot of people on here who have still had reversion issues even with tips that dump water all the way back at the transom.

Personally, I think with a 496 you could still make excellent power with less duration and a LSA around 112, but dial in more lift. A good hyd roller with quality lifters (like the Morels) can handle the lift and fast valve action, but you need good springs and pushrods as well.

Like others have said, Bob Madera at Marine Kinetics would be a good person to talk to about your setup. He is a wealth of information and very easy to talk to. Give him a call at 585-654-8583. He will put you on the right path. Also, there was an OSO member named ThunderStuck who had one of Bob's Gen VI step nosed cams that would be ideal for a 496.

Thanks for the info guys, the engine is going to an engine builder so I won't burn it up again.