Need Help Setting up 7600 on new Mac Pro

I've done fine for several years printing from a Mac G4 thru PS CS3 thru an Epson 7600. Recently I purchased a Mac Pro running 10.6.7, still with CS3, updated the Epson 7600 driver to v8.19, and connected the printer to the new Mac.
When trying to print the same image files now, I can no longer get anything close to an acceptable print from my new system. I've even tried twice to create a custom profile using Color Munki, but the results, no matter what printing profile I select is just plain awful. I've read Mark Dubovoy's recent columns on similar issues, and tried his "work-around" method, but to no avail.
Can anyone suggest steps I might take to get back on track with a good print (other than disconnecting the new Mac Pro, and going back to the G4)?
Michael H. Cothran