I have basically the same rifle as you except mine is a factory /26\ rifle from the same importer. You got yours much cheaper I bought mine new in box and unfired about three years ago for two bills. Mine has the spike bayo,screwed on barrel with locking lug, all matched numbers and all milled parts.

Basically the factory 26 rifles are the only ones that can be reliably dated as to the year of mfg. with the serial number. You may be able to determine by looking for certain features that appear on yours and find the time frame they were added in the production life of the rifle. The thing with the Chinese SKS rifle is there were so many made over so many years by so many different arsenals that it's really had to know what you have other than the individual models.

A good site with lot of info,pics on various SKS rifle and there features. http://yooperj.com/SKS.htm