Pretty neat Buckeye!
So, the ferrule is a blade "V" notch, and the stock has a spike bayo cutout. That certainly points to a replacement stock in my book.
Besides the stock and that blank bolt, everything else on this gun screams early (pre 1964/65) Jianshe build. It could easily be a VN era gun.
The Labanu import stamp and the mismatch stock/ferrule bayo features (along with not having a bayo) probably puts importation in the post 1988 timeframe - after bayos were made into an evil feature, but before widespread bayo lug removal was commonplace like in the early 90's.
It's interesting that this is one of the first VN era M21 I've seen with an import stamp (I'm sure there have to be others, I just haven't seen them). All the M21
No guns were VN bringbacks it seems. The other M21s like your NA could very well have been imported in quantity.
There's good info in your photos. Thanks for sharing!