If you haven't seen this already, check out this guys thread on Ferrari Forum in the tech forum. I think you will need to join to see the pics. He is building a V12 Ferrari 308. But the part you will find interesting is the integrated circuit board he helped develop for MAP sensing that can handle from 2 to 12 individual hoses. So no need for a plenum. Hope this helps.
btw. You project is fantastic. I only come to this site to check out your progress.