Looks like a 1989 or 1990. 1990 specs -
https://waterfordbikes.com/SchwinnCa...0/1990_05.html . Entry level, basically their lowest level bike with aluminum/alloy components. At least it has index shifting. Definitely steps above Wally World.
Brake pads may "look" good, but make sure they're not hardened or brittle. Such pads brake poorly and can damage the rim. I would be reticent to sell the bike as is or just cleaned up, unless you had some confidence that the buyer would replace the tires/tubes and probably brake pads. Markets vary, bikes of this level are priced all over the place, from $50 to $200. With $40 sunk into tires/tube and possibly brake pads, you might get $120-150.