Internal Cooling System

Mine is 1964 2.4L. Engine is out and apart for leaks and other nefarious issues.

Tonight I knocked out the Welch plugs, turned the engine on it's side and flushed it with water and a wire to get the stuff out.

Now....I've been doing engines for a lot of decades....dealt with some of the most troublesome overheating marques in the business.
I thought I'd seen it all, until this.

From the driver's seat:

Core plugs flush through straight across. Good. Side drain works from core plug holes..good.
Shove the nozzle into the water pump outlet in the block (left side), and the water ONLY comes out the deck ports to the head on left side. That can't be right, think I. So flashlight, wire...and I check. Water pressure from pump goes to a closed internal "manifold" along the left side of the block, only comes out into the deck ports on left side. Then through the head, down the deck ports on the right side (and out the inlet manifold, to the thermostat, and back to the radiator) down into the right side of the block to provide water that does not circulate to the sides of the cylinders.

I did it four times to make sure I didn't have something strange in my cigar.

So...question...how does coolant circulate past the cylinders? Am I dealing with some small plugged passages in the bottom of the left hand closed internal manifold?

Somehow we need to have coolant flow in the bottom half of the block, but I can't see it.
NOW is the time to figure this out!

Thanks.
Dave