670's were the cheap, budget version of the pushfeed 70's. Nothing at all special about the rifle. The pushfeed Winchesters are good enough rifles, under rated actually.
I've seen 670's with and without floorplates depending on when they were made. They are generally speaking the same rifle as the PF 70's, just with cheap Birch wood. While they shoot well enough they are only worth around $200-$250 in most places. Some have the exact same blue finish as the better rifles, others used a much rougher finish on the metal. Really depends on when they were made.
The CRF was brought back in the early 90's, but only in the top of the line Classic Rifles. Winchester sold mostly PF rifles right up until they closed the doors in 2006. They changed the name of their budget rifles to the Ranger model. I think around 1980. I could be wrong about the exact year but think a 670 would be pre-1980.
Winchester actually folded in 1979. A group of investors bought the rights to the Winchester name and rifles made beetween 1980-2006 were from the United States Repeating Arms Company. Many will have USRAC stamped on the gun somewhere as well as Winchester. They closed in 2006 and FN, who had purchased the company earlier, moved production into their South Carolina factory and resumed production in 2008. Current rifles are only offered in CRF.
If I owned that rifle, and it shot well, I'd ditch the cheap stock and put it into a decent aftermarket stock and have a decent hunting rifle. But it isn't worth a lot of money.