To switch from a magneto to a distributor you need to remove the 24 tooth #RE454 pump and ignition drive gear from the cam end. You then need to instal a #RE454A sixteen tooth drive gear.
The #RE578 twelve tooth drive pinon, on the oil pump drive shaft, must then be swapped for a sixteen toothed #RE578A pinion. This will complete the ratio change necessary to go to a one to one drive for a distributor ignition.
Don't blame Moline for the mag company's insane need for special ratios to drive their mags. I personally love a distributor ignition for the hot spark and rugged simplicity. When it comes to true batteryless simplicity, the mags are where its at. Most mag swaps today are just fear of the unknown anyway. If grandpa could do it I can surely master it too.
The parts from any R or Z will work as the EE,RE, and side valve 206 engines all were pretty much the same. The main differences were in the lower end, rods, and pistons, to achieve different stroke lengths.
I advise you pick up a repair catalog. I recommend the #R-782L as it has both ignition systems. The transition parts books are great for swapping parts and listing dimensions.