Excellent plan!
Since the new Miche cassette requires a longer chain, you'll want to check to see if the new chain is long enough. Obviously, you'll need enough chain to be able to use the big ring/28 cassette tooth combo.
While the cassette is off, you'll also want to clean and regrease out the innards of your hub, both the freehub cavity, and the 2 main bearings. You may have the cartridge or loose-ball version of this hub, but likely the superior loose-ball version. This will take 30 minutes and require some dental floss.