edit: After re-reading this thread I realized my answer had nothing to do with the original question. Please skip this post and continue to helpful answers!
I have seen bolt on distributor drive gears offered over the years to allow early cams to drive late drive distributors.
edit: found it:
https://www.speedwaymotors.com/Early...Query=91015634
I have no experience with that product, just remember seeing it offered.