The 6500 isn't really an optimal OS X machine.You could put OS X on it...
Unsupported, but in progress. The main problem is that SCSI and Ethernet are not working, which makes installation difficult. Also, will not work with Mac OS X 10.3 or later, because of 603 CPU.
It would be a good proof of concept...The 6500 isn't really an optimal OS X machine.