Sorry, Deve, my simple understanding is that mis-matched metals causes unacceptable wear (in one of the combinations). I see/read no difference in the gear teeth dimensions.

I simply try to get a distributor gear and cam match.

Tim
1954Advance-Design.com
1954 3106 Carryall Suburban
1954 3104 5-window pickup w/Hydra-Matic
The 216 and early 235 engines are not "splash oilers" -- this is a splash oiler.