Do SunTour freewheels have uneven cog spacing?
Freewheels normally had uneven spacing between gears back back then. Until indexed shifting became popular starting in the mid-80s, there was no need for spacing to be consistent. The outer sprockets were threaded on, and the inner ones were splined, so they weren't even attached in the same way. (Aside: I recall a bike shop had threaded together a &quot;9-speed&quot; freewheel and stuck it in their display case as a joke—It was much too wide to mount on a bike. Simpler times.)
I don't remember sprockets having fancy tooth profiles back then: that's an an even newer development to improve shifting.