After going through all the "what-if's", ruling out H-series manifolds for lack of a way to taper the ports gently into the F23 head, and even discussing building a sheet metal tapered plenum and attaching it to the F23 runners so that they're just off the floor of the plenum, we agreed that an OE F23 IM is the only option short of JGE's one-off giant sheet metal manifold.
The question then, was what could be done to the F23 IM to make it more efficient in a forced induction setup. We tossed up ideas of trumpetting the tops of the runners, and even discussed the modifications Nocture had performed on his IM. My tuner thought the job he had done could potentially be quite beneficial if the runner dividers were knife edged, but with no real evidence or reason. Reid didn't agree, and said the best thing to be done would be to trumpet the runners as much as possible like this photo, and let it be. There seems to be more potential to mess things up than to improve them. In the end my log turbo manifold would be the biggest restriction by far. I'm going to inquire into a top-mount mani from AV Engineering, but I'm almost certain it will be cost prohibitive for my goals.
So I think it's fair to say at this point that I will simply get my stock TB bored to 64mm, open the plenum up slightly larger than that, and port/trumpet the tops of the runners as much as possible. Using a different manifold also opens up a whole can of worms with regards thermostat placement and routing coolant lines, which is something I don't want to deal with again.
