Speed density uses the MAP sensor (along with the other sensor inputs) to figure airflow under different loads and air conditions.
Alpha-N is a simpler calibration based on throttle position and RPM, sort of like the old mechanical fuel injection systems.

I only know a little about the Holley Dominator, but it is a top of the line ECU that will do either, and maybe even a combination?

I have the FAST 2.0 ECU for the Coronet, and the Holley is supposed to be even better.

The FiTech will be on the Jensen.