I bought one from Davis Unified Ignition for my Mach1, but didn't install it. I need to run a 14" drop base air cleaner assembly to get the hood to close, and the HEI distributer was to big around for that. I've heard that a 13" air cleaner works fine, but I haven't seen a 13" drop base assembly. It is a quality unit and I wouldn't hesitate to use it where I didn't have fitment issues. BTW, maybe I'm just lucky, but I've owned many vehicles with HEI distributers and never had one crap out, or ever carried a spare ignition module.
I bought one for my 406 off of Ebay. Had some problems with clearance, but, with a 460 in a '70, that is the story with everything...
My motor loves it. It works great, and is also a 2 wire hoohup. One wire for a 12 volt from ignition switch, and the other wire is for the hot lead to your tach.
Had to buy a pigtail from local auto parts store to hook wires up to the dist. Other than that, it is great.
I don't know about it being the "best" but I'm running a DUI and it performs great. Here's a picture:
As others have mentioned, it does ride a bit high, and getting a 14" air cleaner to fit may be an issue. I am running a Victor Jr. intake that has an air-gap style design, so the carb sits a bit higher than on a standard intake, and I don't have any problems with my 14" cleaner fitting.