Presuming they were single PN G650s (one IPSI each).
If the G650s you're installing already had their own port network and medpros and other IP cards, then they're already "built" in CM. Once the IPSI is up, it downloads the config for the cabinet - so the medpro in slot A14 might have nodename medpro_4a14 and an IP in there. If you disable the ip-interface 4a14 to be able to change node-names ip and pop a new IP address in there for the medpro, that's all that's involved in making it work on the subnet at the new location.
From there it'll autodetect the cards in it, or you can manually do that with "change cabinet" to say a DS1 will be in slot 4a10,11,12 if you want to start programming them before they're in there.
Otherwise, if you told me you wanted to move an already working PN from one place to another and you IP'd the IPSI properly, then you don't gotta do a thing beyond follow the cabling to bring it up as the same port network. Fix the CLAN, MedPro and VAL IPs and have fun.
Renaming things, changing the name of location 4 from old_office to new_office, ARS, stuff like that, sure, that's work, but not inherently different than any other gateway type. Troubleshooting can be a pain though.
in /var/log/ecs are logs that'll have IPSI sanity errors. If you're missing QOS on the IPSI, that's when the cabinet gets all jumbly because the control messages are being lost. Its old stuff and might not autoneg nicely or lock down nicely either. So depending on what kind of switching is there, watch out for speed/duplex mismatches. Those'll drive ya crazy. Otherwise, the worst part sounds like the heavy lifting and cabling.