The specifications do indicate that the bike has a Shimano 7-speed freewheel out back. I'm not familiar with the differentiation here--does it mean that I won't be able to install the cassette at all, or does it mean I still can, but I'd end up with a 24-speed fixie?
hub is different, But 7 speed freewheels are still out there as replacement parts..
C&V folks still covet the freewheel hubs of yesteryear..
If you want a Cassette wheel, you can find cheap ones brand new.. the 8th cog requires
4mm more axle width.. to 130 from 126.. frame spread will resist putting a wider axle in.
oh and Fixie is also a different hub, the cog unscrews unless there is a Lockring.
those rings screw on in the opposite direction.