Been in a similar boat for many years, and always kept a few boards lying around, I may still have 1 or 2 somewhere -
This is what worked for me - I have 1-2 PCI M/Bs with PCI to ISA converter boards .. I think I even made my own custom one - I can look up the chipset
required, if that is of interest. I think it was Sunix, but not confirmed. There are also USB > ISA converters ie arstech.com/install/ecom-prodshow/usb2isa.html
Not sure about your driver situation though, or some of the unique ISA features.
I've never had a problem finding old ISA PCs on local trading post sites, but for $20+ bucks each, you can afford to reject a few :-)