I would like some help in determining the width of doors to be custom ordered.

Background: I am restoring and renovating a farmhouse from 1904. In the upstairs bedroom, one end is partitioned off to make a closet. This was done in the 1950's, I believe. The opening is 60 inches. It is a simple, square drywall arch without jambs. The current closure is via bypass sliding doors.

I wish to finish the archway with jambs and casing, and order bifold doors. The door style is 5-panel solid doors; the equivalent bifold would be 3-panel due to the narrowness.

After I install the jambs the opening will be approximiately 3/4 inch narrower. At that point when I have a measurement for the opening width, what is the rule to determine the width of the four individual doors? I'm looking for guidance such as "take the width, subtract X for the end clearance, Y for the center clearance and divide by four", or something similar.

Thanks !

PS We are already aware that bifold doors are not period correct. Thanks anyway.