Hi lowboygmc . . .
The 250 water pump is different then the one used on the stovebolts:
On the later design the heater hose nipple is cast as part of the pump housing instead of the threaded nipple found on the stovebolts. The pipe threads made it easy for me to tap in. But you can still cut the heater hose and install a nipple-tee fitting there.
The key take away here is that ALL hose fittings on the water pump housing are 'inlets' where coolant is 'pulled' by the impeller action. The impeller action in-turn pushes coolant into the block where pressure builds against the thermostat until coolant temperature causes it to open.
Creating another passage for coolant to exit the block - via tee fitting at the block-drain petcock - allows the impeller to push/pull coolant into a peripheral circuit regardless of whether the thermostat is open or closed.
