Yes that is the conclusion I came to after puzzling over different coils yesterday. Without going to the lengths of uncovering the coils to see the wiring I came to the conclusion that those old Pope engines must be positive earth, not negative earth. The wires seem to be coming from the coil the opposite way around to Briggs and Victa. Also I notice that the points snap together on the lower part of the eccentric shaft momentarily, whereas with other motors the points open momentarily on a short wider portion before snapping together. So the whole ignition system seems to be the reverse of what I see on a Victa or Briggs. I am not a technical expert on such things, but to my mind this seems to be pointing to a positive earth ignition system, unless I am mistaken. I've had no problems running the STENS module on different engines, and as you show in your illustrations, most modules are made so you can reverse the polarity simply by connecting the terminals the opposite way around. There is absolutely no reason why an EI will not work on the Pope motor, as there is nothing exotic about it. Just two magnets and points condensor. Providing the coil is good, an EI should work. And of course so long as the timing is right (I have not touched the engine so that should be same as always), it should be simply a matter of working out the correct polarity as Max suggests.
I've never used an Atom module. My understanding is that the newer ones available on the mass market today, e.g. STENS, have largely superseded the Atom EI and are able to sense the correct timing. So long as you get the positive and negative the right way around, there is no reason why they will not fire properly.
Just as a side issue, there is a funny thing about the STENS module and the illustration they provide. The actual module has the negative and positive the opposite way around to what they show in their illustration. They must have wanted to confuse people.
