Thanks to the good advice and hints from you folks, the problem is fixed.
I checked out the floppy drives and kickstart chips, and they were fine. However, I swapped the 2091's hard drive for an old PC-formatted drive and suddently I was able to boot into the my 1.3.2 Workbench floppy disk with the 1.3 kickstart, which was always my goal.
My best guess is that, when booting any of the Workbench Floppys (and many games apparently fall into this category), they will always Mount any drives they find, including the hard drive. However, my hard drive had the International FS which 1.3 didn't have a driver for, thus generating the "insert volume LIBS" prompt.
To be sure, I partitioned the new hard drive as FFS, and "unchecked" FFS when I Quick-Formatted it. Then I switched over to the 3.1 ROM and installed AmigaOS 3.1 on the hard drive. Then I switched BACK to the 1.3 rom and confirmed that the 1.3.2 Workbench floppy still boots just fine.
Again, thank you all so very much for your advice and suggestions. Me and my Amiga 2000 thank you.
- Bo Zimmerman