There are OS collectors out there and you'll be surprised what your new in the box engines are worth. Even if you don't see them in Ebay "Completed items", start watching OS engines in "Toys and Hobbies" RC and they are sure to come up and give you an idea. I've found there are a fair number of well heeled, honest Japanese collectors who don't have a problem paying in US funds.
The mystery Fox is a Fox 59, 1962 or later. It will say "Fox" under the muffler strap. Lok at the venturi where it intersects the crankcase; it is squarish integral with the case (the throttle is dropped in and isn't a Fox throttle). 1957 and earlier would be round. The Falcon 60 (really a 59) had a round venturi with a drop in throttle or CL venturi stack.
Also:
The bottom of the 59 mounts are 3/16" higher than the shaft centerline; the Falcon's are on centerline.
The 59s bypass extends below the mounts; the Falcon's stops at the top of the mount. If you ever mounted a 59, you were probably ticked off the left mount had to be ground out to clear the bypass and then REALLY ticked off to find the spinner ring didn't line up with the engine.
The 59 had 2 mount holes per side with a thin web between them; theFalcon had 3 holes per side and the mounts were a constant thickness. The dual mount pattern (also found on the Eagle 60s) allowed the Fox to fit a competitor's mount pattern, Supertigre I think.
The 59 Just says Fox 59 on the bypass; the Falcon says Falcon, has a US flag, and Made in USA on the bypass.
Attached is a 59 shot, next post will be the Falcon.