You'll be able to date it using the engine id #s on the tin cover, check http://www4.briggsan...tion System.pdf
The tractor will be a few months later than the engine. Ive seen threads on them at a couple differant forums so if you look around Im sure you can find other Huffy owners that may have a better idea of value... but dont expect alot... couple hundred bucks at best I would think, and thats only from somebody that already has one or more. There isnt alot of truely collectable garden tractors, although we see ads all the time from sellers that seem to think there is.
"IF" it was mine.... I would clean it up as best I can, do any repairs required as cheaply as possible... and use it, for many of us the enjoyment we get from old garden/lawn tractors is worth far more than the $$$ value.
"WARNING" .... it is a VERY addicting hobby;)