Heater Core Bypass on 4.6 Motor

Since my car is bi-polar, I search a dozen different forums before I can determine that no one else has ever asked this question, or where to ask, but I think this is the right place to post:

I have a 66 Fastback, running an '01 4.6 dohc Cobra motor, still trying to sort out the numerous issues. One of them is the tremendous flow of heat into my stock heater core, interior temps are unbearable even in So Cal winter, so I want to shut off the coolant flow through my heater core. On a stock 66, you stick a valve on the inlet, shut if off, and your good to go. But somewhere I read that the Modular Motor needs coolant flow to circulate completely through the heater hose circuit or the motor might not get proper cooling. Does anyone know this to be the case?

Also, can anyone please confirm the correct heater hose flow direction, that is which is the water pump outlet / pressure side and which is the return? I have a 90 degree hard pipe coming off the back of the block on the passenger side, and an S shaped hard pipe going forwards on the driver side, but unable to find a flow diagram to confirm the direction the coolant circulates.

Thanks!

Steve
66 Fastback
SVT 4.6
5 Spd
Mustang II Front Susp
Cobra IRS Rear Susp

Oh, forgot to mention, I DO want to have the option of restoring flow to the heater core with either a cable operated shut off valve, or manual valve, so just connecting inlet and outlet hoses together will not be my preferred solution.

Steve