The JAVELIN sailplan remained the same from 1962-86, so sails of any era should fit. I'd check used sails sellers. Possible good idea would be to contact the Javelin Class Association, I know the Day Sailer Association offers used sails to new owners for good prices..... would think Javelin Sailers would what to help their Class friends the same.
But, there are several used sails sellers around, there must be a suit of Javelin sails available at one of them.
I found this listing on Craig's-List, location is in Kingston, MA but maybe he would ship?
http://southcoast.craigslist.org/boa/5050575372.html