I deleted out the solicitation and will not throw any infractions (this time) as you all are new.

The wheels probably won't work anyways. Assuming they came off a newer bike they are too wide (the rear hub) and designed for a 9 or 10 speed cassette. Your bike is the older freewheel technology. You can make it work but then the money gets big, especially for a Free Spirit.

Post #13 by Prathman has the info you need. If your brakeshoes can drop lower in the calipers you can switch to 700C but you need a rear wheel with a freewheel hub not a cassette. These can still be bought new, Nashbar has them sometimes, and eBay should have a number for sale used at any given time. If they have components the vintage guys like they won't be cheap.

You really are better off with new 27 inch tires. There's still a selection around if you look.