Who sells complete closed cooling systems? I assume they range in size depending on application. Cost?
I will need something for 570 cu na motor.

Seakamp Engineering 800-753-4436
SanJaun Engineering 360-734-1910
or
CP Performance.

Mr cool advertised on here

They have a wide selection of kits

You can also check out and talk to Monitor Products in Florida, They make all Mercury's closed cooling units and I have used them with great success.
(800) 334-4591

Best Regards,
Ray @ Raylar

I have used Monitor also. They are near us and great to work with. Mr Cool has been very helpful to user's on here also.
Steve

I've been using a Monitor for 4 seasons cooling the block and 496 merc aluminum manifolds without issue (used exclusively in saltwater).