Not sure I'd do it that way. I mean, you know how they're typically plumbed, so I'll spare you that, and I get what you're going for......I think......and if I did it, I would probably try a "balance tube" across the timing cover plate and exit water at the highest possible point at the thermostat housing. Some iintake manifolds don't have rear coolant crossovers so bank to bank cooling can be a major issue. 

But I would be VERY concerned about the number 4 and number 8 cylinder walls being constantly, and directly, blasted with all the cold lake/river water while the other 6 cylinders don't have that at ALL ..............

I just forsee problems there unless extra clearance, etc given to those 2 cylinders and a lot of forethought/planning for it. And even at that, would upset the balance of the engine I would think (Consistent combustion pressures, compression resistance, stuff like that). Sounds like a solution to a non-problem to me.

In a nutshell, I just wouldn't do it that way. Not for Love nor Money.    I could be wrong, and it may work like an Obama Phone.......... 

Ray

I am plumbing up my 545 in my boat and was wondering what would be the best way to route water out? Use the water ports near my thermostat housing and dump them overboard with a crossover on the timing cover water ports. Or run plugs in the holes on the intake and thermostat housing and dump the water out of the holes in the timing cover, or plug the holes in the timing cover and dump water out of the intake ports? The water is entering the engine through the lower holes in the block on the left and right side.

Normally, water enters the block, goes up to the heads, and the exits at the thermostat housing area. When you say that your water is entering through the "lower holes in the block," do you mean the freeze plug holes or the coolant drain holes? Remember that the head gaskets are engineered to influence water to flow from the front of the engine block toward the rear, then rise to the heads and move from the rear of the heads toward the front and to the thermostat (sort of balance out the flow so there are no hot spots at the rear of the engine). Where the water enters your engine block might have an influence on the water flow or how you install and/or modify your head gaskets.

In a cooling system as plumbed above, water should not exit the front of the timing cover as you are considering. Also, I see little need for a water balance tube on the front timing cover but it doesn't necessarily hurt anything by being there.

LO

I go from pump to 12psi RV to tee into waterpump ports
 out thermostat housing (160 thermostat with bypass)
One line goes overboard from thermostat housing
other line from thermohousing goes to Bassett gate valve into and out headers

Solves water pressure issues and lets water reach good temp in block and controls great to headers

So what setup would work the best? In through the water pump block off plate and out through the thermostat housing, or in through the lower block drain holes and out the thermostat housing?
Thanks!

Checkout water pressure post by quickolds

I explain more details there