Have run a "2 injector" one on my 65 Newport w/ 383 since 1997. Originally the earlier "round top" injectors and "analog" box, w/ O2 box add-on. It seemed to work OK, but no noticeable mileage improvement over the 2 bbl carb.
I later switched to the small 2Di box, harness, and flat-top injectors. I had that system tagged for my Dart, but had to get to work and the other harness failed when a pin pulled out of the connector at the ECU (shoddy crimp design). It has always run funny w/ the 2Di box, requiring constant tweaking of knobs from cold mornings to hot afternoons. If the box gets any sun, it gets real hot and starts missing. Once, on the freeway, the engine slowed way down, and the muffler blew open, then it ran fine (but noisy). I suspect it flooded the exhaust with fuel. I welded the seam back and it did the same thing a week later, at exactly the same spot where there was road construction. I suspected there was a radio transmitter there that messed up the 2Di box. I trust the big "analog" box more, but it is real clumsy how Holley adds the O2 sensor. Indeed, their whole wiring harness big and cumbersome in my opinion. The original "by MSD" ECU design looks more rugged to me.
