Like said Phil Wood freewheel hub, .. 6 speed cassette hubs are [marketing]
made obsolete by now.
So if it were to screw up on the road spares are significantly harder to find.
Freewheels are still being made. just need a small tool
and a borrowed big wrench to remove said freewheel.
7 speed freewheels were made to N+1 cogs, in the space available for 6 speeds.
AND.. Phil & Co. is in the south bay, San Jose.