Hey gang! Kinda ****in' around looking for something else and ran back across this thread. I figured it out, and it was simpler that thought it would be! I sat down at my parts wholesaler and asked for the MotoMite catalog, and low and behold there it was! Right under intake ducting. Cheap and looks pretty damn good. I'm waiting to see how ell it holds up to extended use, but there are other options out there too if it doesn't work.
Looks perfect. I was going to suggest bilge blower hose that you can buy at a marine distributor, it comes in 3 and 4 inch diameter, but it is white generally. It is a lot like clothes dryer exhaust hose. Don
Cars Inc. and Bob's Automobilia both have OEM black fabric vent tube with the steel wire spring in it, any size from defroster duct 2" up to 6" for fresh air vents. They sell by the foot.
This is what I use for fresh air hose to the Air Cleaner thru the headlight openings. http://pitstopusa.com/i-5069300-all...e-duct-hose-275-degree-rated-10-ft-black.html
Corvair heater hoses are corrugated black 4" hoses like you describe. You can get them in 36" lengths from Clarks. Page 101 of their online catalog. http://www.corvair.com/user-cgi/catalog.cgi?function=goto&catalog=MAIN§ion=MAIN&page=101 I could take a picture of mine. I used the cheaper ($26) version rather than the original/reproduction version ($45)