Its something from Fox/Dynamark. Think that was part of the "Banshee" line, it would have been post 1971 and if the large wheel set on it is stock to the bike, probably in the mid 1970's. This is one with smaller wheelset on it to give you a better idea of how it looked:
Brochures and catalogs I have for the 1971/1972 years dont show anything with that large of wheels so I think its problaby middle 70's built bike.
it will be a bit expensive to restore because you're missing the gas tank and seat. if you put a 212 clone on it with an engine mounted tank, that would get around the problem (but not look very stock). an original style seat will be expensive, but you man be able to find an ebay thing and make it work (but that's probably a bit expensive too.) looks like you need tires too. check the rims and make sure they are solid. it's going to cost you a lot of time and money to make this bike work...
I guess it depends what direction you want to go. Do you want to just make it a rideable bike and you don’t care about originality? If that’s the case, and that would certainly be the easiest and cheapest way to go, you’re going to need a motor. You can go to Harbor freight and get a predator motor for about $100 ( which will give you a gas tank too). Then you’re going to need a throttle. He can get that on eBay, $12. Then you’re going to need a torque converter. Again that’s on eBay about $53. You gonna need two brake handles and cables, $25. You going to need a number 40 chain, $15. You’re going to need a jack shaft and probably a 10 tooth sprocket and a set of bearings. That’s about $25
As you can see you’re well over $200 at this point. And we’re not done. You’re going to need a seat. I guess you could make your own and see how that goes. Or you could buy one, about 75 to $150. Do you need tires? New tubes and tires will probably run you $35 a wheel. How are the brakes? Let’s assume that’s OK. Should probably get a rear fender, $25. What about the frame? Are you going to leave it in the current Rust condition? Give it that rat rod look? Or are you going to strip it and paint it? Or go powder coat? All those things cost money
Anyways when you’re all done buying everything, you’re probably going to be in for at least $400 in parts. In a zillion hours in time