The 819 is a closed "D" chamber which can definitely stand some improvement, especially more relief radius around both valves at the bore edge.
The quench distance is going to be important here, how far below deck is the dome @ TDC now?
I've seen some (other) manifolds where the original aftermarket manifold's multiple carb inlets were used as entries for a blower discharge. I think the idea was to balance the flow volume between the front and rear cylinder groups - but I'm not sure it worked. You'll still need a big transition piece between the Eaton and the manifold.
Remember the Eaton isn't position-sensitive, and can be mounted on end (rotors top and bottom) so the discharge is pointing sideways and can use a big 90° "L" into a conventional manifold (instead of having to be above).
Does the M112 turn the right way (I'm wrestling with reversing the rotors on my M45)?
