I have an early 80s Bridgestone road bike with a 6-speed cassette. To switch to a 7 speed, is it just a matter of switching the cassette and shifter? Is the hub spacing, wheel dish, etc. the same? I already have a newer rear derailleur so that is not an issue.

The reason I ask is that my shifter does not work very well and there seem to be more 7-speed shifters around. If it is a simple matter of a new shifter and cassette I think I may go ahead and change it out.