HEI or Motorcraft Electronic distributor

There are a few who run the Motorcraft distributor. They are about the same, but... then you would be bulking it up by adding a HEI style cap. It requires a few add ons but once done you have pretty much a HEI system.

That can be done at a later time, for performance use.

If I had the choice I would run the HEI style.

It's really just whichever you prefer. The HEI is bulky with the coil in the cap. The Duraspark with the TFI upgrade uses a large diameter cap, but no coil in cap makes it less bulky than the HEI. Both work well, even for performance use. The Duraspark ignition module isn't very reliable though, or I should say the aftermarket replacements currently available aren't. Ford hasn't used it since the 80s, and they quickly stopped making replacements, letting the aftermarket take over. Many use the GM HEI module with the Duraspark system, hiding it inside a Duraspark module housing (http://www.fordmuscleforums.com/ignition-articles/492810-tricky-trick-hei-module-inside-duraspark-case.html). That article shows rudimentary wiring also. You don't have to use the TFI upgrade with the larger cap and higher energy coil if you want to keep it stock looking. I'd use the GM module anyway.

I think you made the right decision.  it's simple and  lots of spark.