This is a follow-up on this post [I personaly hate when folks post questions, then don't bother following-up
The sound is in the bottom end. So the verdict from several mechanics is wrist pin, or connecting rod. Whether it's a wrist pin, connecting rod, or main bearing, the motor needs to be pulled and completely disasembled. I'm told if were a lifter it would be more of a ticking, which this isn't. This is more like someone rapping a hammer on the engine. The short story is, we know for sure until the engine is pulled and completely taken apart, at which point since you're already there we might as well rebuild it.
So, the long and short of it is, we're looking at dropping in a new 496 MAG HO. we'll go from 300 HP to 425HP and get Fuel Injection. I don't need to fly in a cruiser, but it'll be nice to get on plane quickly with a boat load of guests.