You may have an issue with the capability of the floppy disk controller not being combatible. The original 5.25 inch floppies at 360K single sided / 720K double sided operated the drives in what was called a single density mode. When the IBM PC/AT came out in 1983 or 84 it had the 1.2M 5.25 inch drives that operated in double density mode. The floppy disk controller was changed from the original PC controller so that it could be run in both the single denisty and doubel density mode. If your customers old medical equipment had a PC type single density controller it will not be compatible with 1.44MB capacity floppies. Altho the drive would most likely read and write in the machine in a 360/720 K mode.

You may very well be faced with replacing the floppy disk controller with one of those SIIG import IDE/FLOPPY add-in cards. An ISA version of one of these is very inexpensive.
You still have the BIOS issue however.

/**/ At one time I designed and manufactured a product called the GiftBox FLoppy Disk Controller that I had for PC upgrades that had a floppy disk controller capable of running 3.5, 5.25 & 8" disk drives in single and double density modes. The board had an extension BIOS on board. Alas this board is no longer available. /**/

There was another company that made addin floppy disk controllers called the CompatiCard. These also had an extension BIOS on board. You may try contacting them at Micro Solutions to see if they can still sell you a CompatiCard. Their current product offerings are the BackPack series of products. Maybe it is even possible to find a way to upgrade the medical product to with a BackPack drive.

Hope this helps
Michael Karas