Just to update on the battery/stalling issue, it's still fine now. I really think that when the electrolyte was low, it threw things out of balance, so when turning on the lights (both on the mag) at idle, with no battery charging from the mag, it dropped the voltage to the spark. If turning on the lights while revving (with battery charging), it didn't stall. I wonder if I had disconnected the low battery from the system, if it would not have stalled. As Mark said, there is some "black magic" involved :o)

Because I don't ride at night, I like having the tail light on the mag because then the brake light is very bright, in contrast to the tail light at low RPMs. When the tail light was on the battery, the contrast wasn't that noticeable.

I have a 69 AT-1E that the PO had just changed the oil in when I bought it, and so when I changed it (as I always do; never trust a PO) I stayed with the transmission oil. Runs fine. If he hadn't just changed it, and if I hadn't found it to be clean and seemingly worry free, I'd have changed it once to Advance Auto Parts SAE 30 non-detergent, run it a while while warm, and changed it again just to get the red out, since the cost is so low. May still do that if I get to that bike before I die.