I've got several older Letour, Letour II, and Super Letour models here, all use 27" wheels, the earlier Letour could have come with steel rims, but I think all the latter models had Araya or Ukai alloy rims. Later models had a nutted rear hub and quick release front. The hubs varied with the later bikes having large flange Schwinn scripted alloy hubs.
Pretty much any 27" wheel with a 120-126mm spacing will work. I've got a rear wheel off a Letour 12.2 right now and the rear hub measures 123mm wide with a 6 speed freewheel.
Bike parts have been going through the roof lately, the last few wheelsets I listed sold for well over $140 for run of the mill 27" sets.
Most bike shops here won't touch anything older, most won't touch anything they didn't sell. Many don't sell parts or do repairs these days, they have the customer leave the bike, then once a week a guy comes around who fixes bikes, sort of a roving bike mechanic. I suppose it saves them from having to hire anyone skilled in any way. (One local shop told me it limits their liability but I think it just lets them hire employees who graduated from flipping burgers).
All of the Letour models were 'Schwinn Approved' meaning they were built in Asia by Giant or Panasonic back then.
If you have the tires and frame set then fixing it is a no brainer to me. You can get brand new wheels, most through are low end Chinese made wheels for as much as what you'll likely pay for a good set of vintage wheels.