A few photos would help narrow it down.

Which, as I recall, may be hard to PROVE with Stevens rifles. Weren't they the ones whose records were lost in a mysterious fire along about WWI? I think I heard there was about to be some investigation surrounding government contracts during or after The Big War, when there just happened to be this fire, you see...

s/n is not definitive. They made so many Favorites that they started using a code letter, and recycling the numbers.  So you can have a 1904 Favorite with a very low number, while a 1898 one can have a higher number.   There are no Stevens records extant to refer to, so we do a lot of guessing.  Best to assume the worst, and make it an FFL transfer or C&R if the recipient is a cruffler. 

I'm no expert on Favorites, (or anything else), but I believe the 1894 variant was carried right up to 1914.   1915 they made the breechblock larger, so those are easy to spot.

Also to add to your 'confusion' Stevens had 'multiple Catalog numbers' for the Favorite and its various arrangements; along with a progression of production changes to the design over its life.

From the Start with the "Side Plate" Action in about 1886 through the various Extractor positions and sizes, the various methods of 'adjusting' or compensating for wear to the pivots allowing the Lever to 'Droop' when the Action was closed to variations on Breech block widths and contours on internal surfaces to the Action.  I believe there are books and books of identification information that collectors have amassed on the subject.

Practically, Wisneer's has a Section of his web site that lists variations in teh parts between Actions.  Jack First publishes a Three Volume Catalog of Action diagrams and part lists to help the Customer Identify the needed part as accurately as possible.  Muzzleloader builders Supply does list (off line) replacement pivot screws for the Various Stevens, Remington, and other Rolling/Falling block actions, call them for an Email copy of their list.

So far I have '1894' Favorite Action/parts that seem to span a wide range of the potential variations, and I am NOT a Collector, as I am looking for Shooting Examples not Collector Examples.
A Side Extractor Breech Block I have measures .435" in width.  Several 'center Extractor' Breech Blocks measure .450" to 480" in width with differences in the Contour of the front 'ears' and bottom and these are all nominally for the 1894 Favorite.
Levers were also made both with and without a Spring and Plunger to act against the bottom of the Link to keep the Lever  from 'Drooping'.
One receiver I have also has a leaf Spring mounted in the lower front interior to hold Tension on the Breech Block.  and I have two barrels that have an adjustable Ring-nut to 'tune' head space, again to keep the closed tension on the Lever and linkage to hold the action in a locked condition.

Best Regards,
Chev. William