1989 318 TBI ignition questions

So here's the questions of the day, because some of you are smarter than me.
1989 318, factory 2 barrel throttle body. I'm switching to a 4 barrel set up.
Do I have to convert the ignition to a stand alone system, such as a mopar electronic set up? Pertronic, MSD?
If I leave the ECM plugged in, other than a check engine light on the dash, will the original ignition function properly? There is no crank sensor.