I'm sure it came with 27" wheels. You could put a 700c fork on it, but the cheapest route to go would be to buy a chrome, 27" Sunlite Hi-Ten fork. You'll need a JIS headset with that fork, by the way. I bought one for my wife's '84 Peugeot mixte. It's not the nicest fork in the world, but it was only $25.

If you choose that option, I'd order one from my LBS (J&B Importers is the distributor) since it would need to be cut and threaded. You could, however, leave it long and use a bunch of spacers. I did this on my wife's bike since she likes the handlebars high anyway and this allowed me to use a normal (not Technomic) stem.