Interesting idea, but I suspect Timbck2 is right
Apple Macs prior to G3 ran on Motorola chips and their operating systems came partly built-in on ROMs, and partly on floppy disk.
These days emulators can re-live those olden days fairly easily however building a real OS 9 Hackintosh would be hard.
Part of the problem being those ROMs. Yes, you can create software images of them to run in emulators but a physical machine would need real, genuine hardware ROMs.
There were PCI boards designed to hold these chips fairly easily available - probably still are. Take a look here:
www.emulators.com/softmac.htm
However there's is more of a hybrid emulator/VM using genuine components, getting to a full standalone OS 8 (or 9) Hackintosh maybe a step too far. In those days hard-disks were SCSI and Mac floppy disks unreadable by PCs or their hardware. OS 9 didn't make it as far as G3 remember so wasn't even PowerPC. Apple's own "Classic Environment" was an emulator for Motorola on G3/4.
Funnily enough I actually still have two old magazines which explain the OS 8 process (PC Express if anyone remembers it).
I haven't checked recently but the OS 7.5 system was given away as a free upgrade by Apple that allowed you to build the machine. You'd need a genuine OS 9 media set.
Tricky, all of this, but it would be great if someone managed it.
Might just be so much easier to BUY an old Macintosh or iBook G3/G4 and get the whole lot in one nice, easy and relatively cheap bundle!