I'd probably go with a wheelset.
Vuelta Corsa Pro II 11-Speed Road Wheelset
+
SRAM Pg-730 7 Speed Cassette
+
spacers. Unfortunately Nashbar doesn't have cassette spacers, so you could go to Amazon, I reckon
https://www.amazon.com/Wheels-Manufa...ssette+spacers
Then you'll need a cassette tool.
Have a 12" crescent, 24mm or 1" endwrench, then just get
Park Tool FR-5.2G Cassette Tool
Otherwise, go with:
Nashbar Cassette Lockring Tool
Wheels will be a little narrower than rear end of the Denali, but the 2.5mm squeeze of each dropout shouldn't be a problem
The 12T small cog will yield a slightly higher gear than the 14T which I think is stock on Denalis.