Some of us with older motors still have the Sherwood style 4-port water pump system. I understand they are used on small block Chevrolet motors, including the 283, and also on the Chris Craft 430 and 431 motors. They are expensive, but they’re still available new and parts are still available too.
These pumps use two impellers, and essentially two complete water pump systems, inside one housing, which is pretty unusual. I have one on my speedboat, and I can provide detail photos of any part, outside or inside, if anyone needs them.
You will note, what are referred to as “inboard” and “outboard” ports on the drawing. It is my understanding, that one outboard port and the adjacent inboard port are required to be hooked up as side by side “incoming” lines, and the remaining two are “outgoing” to the motor. See the following photo which suggests this is factual; with two outboard ports closest to the camera looking as though they are drawing water in from the bottom of the boat.
Another view of the pump as installed on a small block Chevy flywheel forward installation. These are normally cam driven, and they are hooked up on the aft side of the OEM generator. The photo above shows the pump being driven directly, and an aftermarket alternator installed. Obviously the pump doesn't care how it's driven as long as it turns in the proper manner.
Here is a detailed diagram of the pump.
