There are still ISA slots in new systems with fairly modern processors and plenty of RAM, if you don’t mind buying specific models of industrial PCs for way too much money.
Or maybe you need 4 PCI and 9 ISA for some reason. DuroPC’s got you, if you can drop $1800 on a system with the same generation of processor. https://duropc.com/product/r810-4p9i-4
For $1100 or so you, too, could have a 4th generation Core i3 machine. https://www.rampcsystems.com/product/2-isa-slot
Or maybe you need 4 PCI and 9 ISA for some reason. DuroPC’s got you, if you can drop $1800 on a system with the same generation of processor. https://duropc.com/product/r810-4p9i-4