I took a look at the 6v starter I have, it does not twist while the solenoid kicks it out. Spend some time with a file and reshape the end of the gear
1963 Chevy C30 - 292 I6 +.040" 10.78:1, SM465
1978 GMC K2500
"Four gears with a granny low and six cylinders straight in a row."
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