Thank you for the serious replies.
My consensus at this point is:
1. increasing the size of my separated LR plenums would have little downside, unfortunately there is no easy solution for that because of space and headers.
2. OEM LR plenums are rather anemic sized, Since I am going to EFI throttle bodies, I have room to add a 1-1.5" open spacer, or at least experiment with that potential solution.
3. Hadn't considered the ignition vacuum signal issue , I might be able to just plumb the signal line to both of the small OEM plenums for a summation signal?. Not sure how much smoothing takes place in the vacuum sensor or software to reduce pulsing..
4. I'm inclined to remove the remove/eliminate the OEM crossover, doesn't seem yet as a bad move, but does have some risk/uncertainty in the outcome.


Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.