From your description, it sounds like a letter series gun to me, imported in the late 80's to early 90's. Photos of the receiver would be needed to be certain. It that's indeed what it is, prior to being chopped, it certainly was a C&R gun having been built in the '59-'60 timeframe. Now it's not so much a C&R as it's not in original military condition (nor will it ever be again w/o performing a barrel swap).
Letter guns originally took blade bayonets. Your stock is cut for a spike, so as of right now, that is what "fits". I can't tell if the stock S/N is matching, but I suspect it is either a blank replacement (common on paratroopers) or a restamped replacement (again common on rearsenaled guns). Original stock would have a side swivel, small blade bayo groove, and 1/4" tall by 1/5" wide S/N font. I also can't tell if the stock ferrule attached to the barrel has been widened to accept the spike,some were and some were just left alone. Spike vs blade ferrules are noticeably different, this gun with the original blade bayo would have had a "V" notch ferrule:
Para spike bayos are available, you have to look hard though. Gunbroker or eBay are going to be your best bet, retail outlets stopped selling SKS parts a while ago and now only have the occasional piece part for sale. Even parts sites like Numrich seem to be out of the majority of what people need. Expect to pay $40+ for the complete assembly as they command a bit more than a typical full length spike would. Alternatively you could cut / grind down a full length spike if you wished to take on a project.
As for whether the chop was done in China or stateside, with that importer (Briklee Trading Co.), it's very likely that it was done in China by the exporter as the replacement bluing looks pretty consistent and done well to me. What does the front face and crown of the muzzle look like? Stateside homebrew chop jobs can be pretty crude up front. Gunsmith performed jobs are usually quite a bit better and usually indistinguishable from those done in China.