Man, thought you already had been there. Two easy checks anyone can do.
Condensors. When idling look for possible arcing. Some tiny sparks are OK.
For clarification see this video.
In this video left condensor (1+4) is bad and causes arcing which means little or no spark at plugs 1+4, right condensor (2+3) shows only very little sparks and is good.
Breakerpoints. Check carefully none of the connectors at the breakerpoints is too close to the plate and so can make ground intermittently when engine vibrates. Failure of a breakerpoint or condensor would affect two cilinders however, 1+4 or 2+3.
Looking at your plate I see the original TEC plate and aftermarket, Daiichi breakerpoints.
If timing is right, folks that say you can't get the adjustment right with Daiichi, should have look at your picture. So to see, setting of all plates and breakers is nicely in the middle of the range. Unless you suspect the timing to be off, I'd leave it as it is.
Could there be any water in your fuel?
I've given it liberal doses of seafoam as well.
I don't know Seafoam and I don't know if one can be too liberal with it although I suspect not.