Real good point...I tend to do the same thing as far as putting a larger bearing area on the SA. Same deal..that slot makes me nervous. Course I usually make oversize aluminum spacers. Sometimes I'll put a hardened washer on the bearing side.
Yeah...wheel and bearing spacers would be a good use for hardened steel.
I could also go to a smaller chain size now, anneal the sprockets, do the machining, reharden it. Last time I tried to machine a hardened counter sprocket it didn't work out so good.
I also want to use a high temp oven to start melting some aluminum and casting some small one off pieces.