The steps to upgrade, beyond simply installing version 8 to a new directory, licensing it, and starting it, vary based on how things worked in the previous release.
Points in the application where it ran uf70c or uf71c should be changed to run uf80c. In the BBx world, this is typically found in the config.bbx alias lines.
If the rule file was specified with a uf70c -f option and without a full path, that file must be copied to version 8's location. If it was not specified, the install relies on a default rule file, which is specified in uf80d.ini in the rulefile= line or maintained in the Server Manager configure option.
Any files that the rule file depends on, like logo images, should be copied so they are accessible to version 8.
If you relied on ghostscript or image magick, those must be configured in the uf80d.ini file, like they were configured in uf70d.ini.
There may be other things as well, depending on the overall configuration required. Assuming the print output from the application is the same, the rule set detection logic should work identically in 8. Maybe the issue is simply finding the proper rule file, as could easily be the case if you used the default rule file method. If you need further help, we can do a gotomeeting later today or you could send us specifics on the uf80c command line you run, along with the uf70d.ini and uf80d.ini files, the rule file, and a sample print job that doesn’t detect under version 8.