Consider any chips plugged in backwards to be junk. Any backwards eproms are without a doubt toast, If the cpu was backwards it's likely smoked as well.
Backwards eproms or cpu shouldn't damage other chips, so I'd start with what you know to be a problem. Replace any chip that was installed the wrong way and go from there.
The remaining eproms you can check if you can get your hands on an eprom programmer.
For the eproms that were in backwards and the ones you suspect might be an issue, drop Stephan at
www.hobbyroms.com an email (assuming you don't have access to a burner). He runs a great service and will hook you up with whatever you need for programmed roms.
D