I can't help you much but one of the fellows on the Brit Bike website might. I've seen some of those maglita set ups and they are funky, if that is what you have. RE 350 & 500 singles in that time frame were mostly using Lucas magdynos then later the N1 mags and various distributor battery ignition set ups but I don't know the interface arangements well enough to be of any help on the 250 singles. Also Hitchcock's might be able to help.