HI:
Thanks for the replies.
I remember from my distant past reading about the 807 manifold I have.
The part that caught my attention was "which is difficult to modify because it is made of cast iron".
I was hoping to hear from someone who had tried as I can work with cast to steel pipe welding.
I have, waiting in the wings, a steel header plate crafted from the exhaust gasket as a template and flex stainless pipes going to a connector(4-1).
Artful yes, functional no.