I don't know about resident expert, ha ha.
What I can tell you, if you don't already know, the TBI is set up to fire the injectors synchronously, meaning one fires then the other one does. If you look at the intake manifold and the ignition firing order, each injector fires when the cylinder's intake valve it's feeding opens. Maybe a useless tidbit but, kinda interesting to me.
I have the Edelbrock 3704 performer TBI intake manifold with a 46mm TB (they say flows 650 CFM) 20 PSI spring, Summit Racing 162108 heads (2.02/1.60 valves), Lunati bump stick with 1.6 full roller rockers (yada yada yada), where I do see that my MAP is only ~90 Kpa (plus it's running pig rich according to my WBO2) with WOT @ 5200 RPM (I do see 100 Kpa at lower revs) which may indicate lack of flow. I still need to tune it some more to see.
A bigger 4 BBL manifold would probably flow better but, may not get enough fuel to the corner cylinders. I saw on Engine Masters (I think) where they had to re-jet the front and rear bowls on a dual quad tunnel ram manifold to get enough fuel to the corners using a WBO2 sensor on each cylinder. We don't have that option with TBI, obviously. If I were to go with a 4 BBL manifold, I'd use a good adapter that will help with flow like this one instead of a simple plate adapter. Does any of this make sense?
www.ebay.com/itm/233652976731?hash=item3666cd7c5b:g:eUQAAMXQfj9SMzuY