Just got an email from Big Jim on the ARD shop address/phone (which he also posted here)...Thank You, Sir!
I had an ARD magneto conversion fitted to my old Triumph -
It did indeed use a Fairbanks Morse magneto, with the ARD conversion made of aluminum, using a cog belt. IIRC, points and belts were available from just about any auto/farm parts store. The old farm tractors used them. The whole setup cost about ~$250USD, back in the '70's. The magneto itself was the same one Joe Hunt used in his conversions, although the BSA A65 is the only one I examined. The basic farm tractor mag polished up nice.
On the Triumph, ARD made a special timing cover with a drive enclosure for the belt drive, with the mag fit in front of the cylinder, and cog belt drive wheels. IIRC, timing was 40* BTDC. Measured with degree wheel, and TDC indicator. (My memory might be off...that was a long time ago...)
I came across the ARD instruction sheet not long ago, but have no idea where it went...although I still have the Glenn's Triumph manual (go figure!)...