Yeah, the only sign of refurbishment I see is the stock without a serial number. The bolt carrier serial number font matches the font on this 1958 Tula and has Russian inspection marks. The laminate stock is correct for the era of production. It's a beautiful SKS-45.
With no import mark and residual paraffinic preservative, RMs Canadian crossing hypothesis is plausible and probable. Though it seems less likely, it could be a Vietnam bringback from a cache (given the condition), and that would make it truly remarkable. Does the Chinese sling have any markings? It looks like an old authentic one. It'd be interesting to see if there's a date on it that could place it in the Vietnam era, or not.
In any case, it's a real beauty at a heckuva good price! You paid, easily, $300-400 below market value on that one.