Other than looking through the Ads in a copy of Hemmings Motor News, either hard copy or online:
http://www.hemmings.com/, you might try doing a google search for a Willys enthusiast forum. about 40 years ago I sold a Willys sedan (a 52 I think) to a gent who was a member of the Willys (or Willis) club.
A quick search for "jeep willys" got me:
www.willysjeepparts.com/
www.jeepdr.com/
www.willysamerica.com/
www.jeepsunlimited.com/
forums/
et cetera....