Back when add-on EFI was still new, it was about "1000cfm" flows, horsepower, and such, not improved engine efficienies, by observation. I bought one of the earlier Holley 2bbl EFI units to go onto my '80 Newport 360 2bbl engine. EFI (TBI) to go with the factory electronic ignition control module. A "full electronic situation", as I envisioned it. All turning was analog and WOT turning was done manually, unless you bought the add-on Oxygen Sensor kit. Came with universal wiring harness and instructions. That was "state of the art" back then, which makes the modern self-learning EFI units look like little more than it would take to replace a carburetor, by comparison. It's all still in the box, as I bought it for about the same price that a new spreadbore carb costs now. One of those "future projects" that's still in the future. Seems like it's rated at less than 400 horsepower, which would fit a lot of things, once the TBI is adapted to an intake manifold.
Enjoy!
CBODY67