Are you aware of any secondary charectoristics that would help determine the original year of production? (Assuming the gun has all original parts, as most seem to be very close.)...For example would it be safe to assume that if the gun had matching bolt, reciever, floorplate, and the stock featured an early flat style buttplate that it was in fact an earlier k98 model?
That would be a pretty good assumption. Most of the rifles I've seen did have their build marks intact though.