get the pluck out of here,really.?round is so much cheaper,alittle repiping and your done.

The Merc bell housings do have a fairly small transfer port for the water to cross from one side to the other. the Eickert/Hardin bellhousing has an 1 1/4" hose that jumps from one cooler to the other so there is no issue. As you mentioned, you can add a jumper hose to the Merc bellhousing to help it out.
When I use the Hardin bellhousing, I will use a 2 stage pump. I feed the pump with a 1 1/2" hose and come out with (2) 1 1/4" hoses. One hose goes to each cooler. I use the transfer hose that runs from one cooler to the other as a balance hose to equalize the pressure in the coolers. I bring the water in the bottom and out of the top of the cooler. That way it fills completely. The water comes out of the top of the cooler and runs to the crossover, which has 2 inlets, one on each side of the engine. Plumbing it this way allows each cooler to get fresh cold water. I'm not double passing the water from one cooler to the other.
Eddie

Good info Eddie. Thanks!

that is what i had,the bellhousing cooler is a much cleaner look,and i am kaking a lot of changes on my current project.

I think you should try the 8 plates first. I have 800hp on a single 8 plate with NO thermostats, BIG oil hoses and HP6 filters and after a 4500rpm 30 mile run see 185 max temp.Note I only lake boat and rarely see cold water temps. the combo has been together for 5 yrs. Bob Teague advised me to set the system up without thermostats as to keep things as simple as possible given how I boat. Merc bellhousings and another 8 plate not plumbed in cause i just dont need it with crashboxes. I also feed my intercoolers from the top of the bellhousing on the seapump side. Good Luck

it will be interesting how my two motors do.port has the oem style bellhousing plate coolers,the starboard side is round coolers.both motors are bulit 496,s.i will soon see what does a better job if any.thanks for all the info guys.

It's alot up front, but once you have the covers, the actual cooler elements are only $275.

They have some advantages, like being able to open them up and clean out the seawater side, and then you can just throw away the cooler element if you rebuild the motor.