I'd definitely go with 700c as you'll have better tire choices.

Price wise and quality wise, it's tough to beat these wheels from velomine at $109:

Sun CR18 Road Bike Sealed Bearing 700c Wheelset 126mm Rear [072774744381] - $109.00 Velomine.com : Worldwide Bicycle Shop, fixed gear track bike wheelsets campagnolo super record vintage bike

The Sun CR 18 rims are strong and will look right on a vintage bike. Just get a good quality tire. That bike can handle a 28c tire and I think it can handle a 32c.