A glassed 16 foot canoe with long decks like that may not be much lighter than your 18 foot Otca. This doesn't look like an Old Town to me since their long decks were usually more arched. The boat at http://maine.craigslist.org/boa/3895158241.html may be a Penn Yan but it still seems overpriced at $50. Good luck,
The table at http://www.wcha.org/catalogs/old-town/dimens-1.gif shows that most Old Town models of 16 foot long canoes are about ten pounds lighter than their 18 foot long versions. The center trim on the deck like this is usually found on canoes from the Charles River area builders. The images at http://forums.wcha.org/showthread.php?4175 show a known Old Town with a different style of long decks from the 1920s.