I've been playing with a '02 Regal GS as a daily driver. I have HP tuners, which let's me program the ECM and record data. Make a ¼ mile run, review the data, then tweak the timing and fueling. It's great.
I am considering using EFI on my '82. Not for fuel economy or better drivability, but for the data recording and control over the ECM. The stock '82 ECM is too slow to useful for anything. I've tried adding a data recorders, and that's been frustrating too.
I wouldn't recommend a simple EFI. For me, it must integrate with a laptop for data recording/viewing and have control over the timing & injectors. If I could record and control my '82s engine like the '02, I'd be very happy.