The intake ports (4), each one feed 2 cylinders, very poor design. Sum, we already have the TPS on the carb, no choke and mechanical secondaries. We are going with 55 pph injectors in the ports and 95 pph injectors above the blower.
Will you use 8 port injectors or 4? Problem with shared intake runners is the valve timing. . . . for example . . . cylinder one intake opens, then 180° later cylinder two intake opens, then 540° later cylinder 2 opens. You must inject only on the open valve. Otherwise cylinder one will run rich and cylinder two will run lean. I'm using a 1-6-2-5-8-3-7-4 firing order.
I'm not sure I'm explaining the concept well, but imagine a constant flow injection system as an extreme example. #2 intake opens 180° after #1 intake opens . . . there will still be some flow into #1 as #2 begins opening. After #1 is fully closed, all the fuel flows into #2 until it closes . . . then it begins to puddle behind the closed valves. When #1 opens, that puddle dumps into #1 along with the fuel from the injector while the valve is open. Since cylinder #2 starts to open while #1 is still partially open, there is no puddle of fuel . . . so cylinder #2 receives less than half as much fuel as #1.
Assuming a redline of 6000 rpm, you'll have about 4 msec to inject your fuel but will require sequential injection . . . not currently available on the MegaSquirt. There is a router board under development for the MegaSquirt II that may become available next year.
http://www.megamanual.com/ms2/Jim