EFI considerations for a 1970 383 with very mid cam

It's possible to get around the two IGN terminal issue by using a relay with a capacitor across it's coil, making it close slowly enough to stay on while switching terminals.

But let's back up a little: What are your goals and priorities for the system? Are you trying to get a little more drivability on a budget? Add features that will help you win drag races or autocross? Tune for forced induction? Drop jaws at the local cruise night? The TBI setups discussed can make sense for the first goal, but some of the others might call for a Dominator, Haltech, MS3, or other choices.