If the steering wheel looks like the top pic it is a 1958 with woodruff key shaft.
If like other pic it is a 1959 with a splined shaft.
I think both are tapered but the old geezer memory isn't so good.
If you have the time soak with PB Blaster or similiar. Bump the wheel both ways to break it loose.
BTW these are 300 & 300B pics but the 600B are the same configuration.