In advance, my excuses for my spanglish:

I use a compufire unit in my 121 some years ago. By a year it work like a charm.

But, an the 13th month (omen) it fail, left me stranded in middle of the city.

Many ignitions units (from the 70s) is located into the distributor, and due it, suffer of heating and risk shortcircuit on the long term.

Now, I use again points on my distributor, but I add a MSD5 "ignition box" between it and the coil, it running fine up to today (as a safety blanket, I have a little cable with female terminals on both sides for replacement of the ignition box on case of malfunction: it will allow me to return limping to home -using points- in case of box failure).

If you want to use the small ignition units, please, have another one at hand as a replacement in case of failure, or, set another distributor (with points) for in-field-replacement.

Photo: In my car, the ignition box is red is unbostructely located over the passenger side wheel arch on the engine bay:
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Joaquin / Rojo 121 / Lima