Water circulates as you said above. Rear of the head is near the hottest point in the system. 270 and 302 engines in some large trucks had a "bypass" tube from through top rear of the head to the engine side of the thermostat housing to provide extra water flow in the rear of the head. It also prevents the air pocket that occurs in that area when the coolant is changed.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
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