[Bad70sbchevy]

You can always run the ignition system separate from any EFI system. The main issue is usually on a aftermarket system, it needs a sensor to tell the crank rotation (for sequential fuel injection) or as basic as an rpm sensor. Mass air flow systems are usually better than a speed density unit, but there are rarely aftermarket kits for this. A basic speed-density unit is typically what you get with most aftermarket kits (Holley, FAST, Eldebrock, etc.) which only require a pressure sensor and temp. A really primitive system is an alpha-n system which is just creating a map from throttle position and rpm. A nice thing about the newer aftermarket systems is they come with a wideband O2 sensor and can self adjust themselves (closed loop system) without having to run to the dyno and create fuel maps on your own (I believe the FAST and the Holley Dominator kits do this).

Back to the ignition system, you can probably run your MSD dizzy as is with whatever fuel injection system you use. Now if you want to be able to still make an ignition curve electronically while using your same distributor, you can hook it up to a 6AL2-Programmable Box and you'll be able to tune it with your laptop. Also you can buy the MAP sensor and even make your own vacuum advance curve as well since the manifold pressure is on an absolute scale. Either way you can still run your existing ignition setup with just about any EFI kit.