I have an 82 Fuji Supreme as my summer commuter. I bought some 27 inches 1 1/4 wide Nashbar Prima 2 tires for this. They have a Kevlar belt, so are pretty reasonable on flats and I believe I paid only $10 each for them.

My only problem is that the rear wheel seems to maybe have a slight bend in the axle. I think the older freewheels aren't as solid as today's freehub and cassette design.