Whether your "Model 98" is the long (and more uncommon) Gewehr 98 or the short Karabiner 98.
Whether, in the case of the Kar. 98, it's a pre-war or wartime production model
Markings. A lot of the Soviet capture rifles were imported into the US by CAI and others, and have had the markings scrubbed, which negatively impacts value.
Whether or not parts are matching.
Whether or not it's a rifle which has been 'duffel cut'