Check out the PowerJection III system from Professional Products. It may be the same system as the Retrotekspeed mentioned earlier. I know Pro Products sells through Retrotek. Summit carries it as well.
I've been eyeballing the system for a while now. I read an article on its install in Mustang and Fords magazine a couple of years ago. The article indicated a simple install, basically like a carb swap (4150 style flange to fit most any 4bbl intake) while adding an electric fuel pump, regulator and return line, and a handful of electrical connections and a clamp on O2 bung with sensor. The article, as well as online videos, describe the initial break-in as letting it idle to temperature with a few slow rpm pulls in neutral, then about a half hour drive around with various accelerations and stops of increasing demand to establish the tune. Further tweaking, if desired, can be done via laptop computer across a few dozen points of tune. There are also some YouTube videos of costumer installs.
I've found nothing negative about this kit, though I keep waiting for some bad press. It seems to be the most versatile, tunable, and elegant "box" kit on the market. It even looks like a double pumper. It's designed for V8's with a 750cfm flow capacity, but has been successfully run V6's as well (displacements were not listed). I would think it should run just fine on our L6's since the fuel discharge is independent of vacuum signal. Supposedly, it's even good to handle 2.5bar of blow-through boost as well as nitrous.
Anybody tried one of these?