An SKS is an IMPORTED rifle.  As such, you not only have to comply with the 1994 AW ban, but also the restrictions added to the GCA86 in 1989 (usually referred to as the 1989 Import Ban).  This ban restricts semi-auto rifles from having ANY of the following "military features"

- pistol grip (thumbhole is okay, though, under THIS portion of the law)
- folding/collapsable stock
- grenade launcher
- flash suppressor/threaded barrel
- military bipod (note: this was replaced with "bayonet lug" in the 94 AW ban)

In order to be "pre-89-ban", you must be able to PROVE that your rifle was IMPORTED before 1990.  When it was manufactured is irrelevant; only the import date matters.  And, in almost all cases, unless you were the original buyer, there will be no way for YOU to determine the import date.  BATF will have the paperwork, of course, but they will NOT tell you.

Note also that going to a fixed mag does NOT exempt you from the above restrictions under the Import Ban.

One way around the Import Ban is to replace enough parts with US-made parts, which was recently (about 2 years ago) made possible with the production of several US components.  With enough US parts, the gun will be a domestic, and then you'll only have to comply with the AW ban (your gun will be considered post-ban).  And once the AW ban expires, you'd be good to go with whatever features you like.

As it stands now, your rifle is absolutely illegal, and ATF DOES prosecute 922(r) violations on a regular basis, unlike the AW ban.

-Troy

Quoted: The key is weather or not it was in a prohibited configuration prior to September 1994.

That's false.  This is an IMPORT, which has additional restrictions, as I've outlined above.  Until you can satisfy the Import Ban rules, the AW ban isn't an issue.

-Troy