1 I solved that problem several (15!) years ago.  I have a dual 51/4" & 3 1/2" drive that fits in a half-height slot. Shows up as A: and B:

Also, I never throw away a HD when I upgrade.  I have several from 800MB to 10GB on hand as spares. I've a couple of 386s running an old linux (Red Hat 7) and doing quite well.

2 My problem is that I tend to run stuff until the wheels fall off, which means there aren’t a lot of spares lying around:  This particular machine is now on its third hard drive, as well as its second power supply and its second b: drive, and its third keyboard.  (The other Legacy Box is up to  hard drive #2, b: drive #3, mother board #2, and will have CD-ROM #2 whenever I get motivated to change it.)

Never seen a dual-floppy drive like you describe.  I assume it’s now a collectors’ item!