There have been hundreds of systems for pocket doors over the years.

Counter wights to lessen the work of mioving the doors are secondary to how they move.

Tracks in the floor were common for a long time.

Parallelogram systems saw some use (large metal assembly in the pocket), and hanging tracks are common now.

What system the doors use to move will determine how to get them back into operation.

If your tracks are still there, I'd imagine the job will be a lot simpler! My doors hang from a track in the top of the opening without any track on the floor--of course, mine are only about 7.5 feet tall, and don't have any weights to help open them.

On mine, there is molding next to the opening the door slides into, and that is removable with screws, giving a wider area to attach the doors to the tracks. On some older systems, you would have to remove the casing on the top of one side to access this track, but there were lots of different systems, so you just have to look at how the door trim is put together. My house was a bit later than yours, built in 1908 but I looked at a house twenty years ago when house hunting which had three sets of pocket doors--all hung from the top with no lower tracks, and that house was built in the 1890s.
I lost out on that house and it is now gutted and empty last time I looked. (I had not been told right then that they showed it to someone else, and I'd have offered right then and not waited until morning. My offer was accepted as backup, but the other went through--pretty sure they were salvagers since it was never moved into, and was gutted. I was one of the last to see it all original--I would have bought it from the son and daughter of the original owner, so nothing had ever been painted over or modernized.)