I don't think that you understand how a heat riser operates on an inline six. There is a valve inside of the heat riser box which directs hot exhaust towards the underside of the intake manifold to heat it up to improve operation while engine is cold. Once the engine warms up, the bi-metalic spring relaxes allowing the counterweight to move the valve, redirecting the exhaust away from the intake and straight out through the exhaust manifold.
I am guessing the heat valve which you are referring to is what was used on V8s. That was located on the right exhaust manifold at the exhaust pipe. When this one is closed, it redirects exhaust through a port in the intake manifold then out through the left exhaust manifold. While doing this, the exhaust heats up the intake manifold for better cold engine performance.
Putting one of these on your inline 6 exhaust pipe would be like stuffing the tail pipe with a potato.
Carl
