Since my beginning, in this hobby. I see limits that should be considered as new area classes.
What about motor classes combined from 1960 to 1968. From these groups any 3. 5. o r 7 pole armature would be legit. to modify
In brushes, rewinding awg wire sizes, magnet enhancement, and gravity or digital balancer balancers.
lets call all this craftsman vintage era kits or scratch built