I think that the only way you will get true circulation with an Offenhauser intake is to run coolant into either side/port in a dual-port base-plate and have the coolant run out-the-other-side/port.
When you use the exhaust header connection/connections (with either the one-port base-plate or the two-port base-plate), you do not get true circulation - you get heat transfer.
Many people believe you need some heat, somehow, to the base of the intake manifold.
That being said, I have never used the one-port exhaust-heat base-plate, but I would guess it works fine.
