I doubt it has to do with gear extension - should I have an engine failure you can bet I'll be holding up that gear override if I need to. I also don't think the change in wing loading is enough to explain such a change in best glide speed. I'm going with the transposed digits theory too.
I fly a 1967 arrow-1 with the hershey bar wing and the 180 lycoming. Interestingly enough I cannot find the best glide speed in the POH. Vy is 100mph, which is about what I would use. The best glide in an arrow-1 is still dismal. In normal ops, there is just about no such thing as too high or too fast, once you get the gear & flaps down, power back and RPM up. The engine failure section in my POH advises that the most common cause of engine failure is fuel, and that you should monkey around with the fuel selector, boost pump, and mixture. Apparently if that does not work they think you should give up.
-- IFMU