No need to rebuild anything.
If you copy everything in exactly the same directory structures, you can just point MC at the new drive letter, or UNC path. Use the Rename, Move, and Copy files tool in UPDATE mode and tell it that the files now in a different place. If it's as simple as just making a drive letter change (for example), then the RM&C command will be very easy.
...and because this is just an update, the whole MC RMC process should take just a second or two. Then MC will be pointing at your files in their new location.
I would probably use something like Free File Sync to do the copy. That way you automatically preserve all of the directory structure. Plus it's stoppable and restartable and won't lose it's place or have to start over again.
Then when it's totally done to your satisfaction, you can run the RM&C command to update MC. Make an MC database backup before you run the RM&C, and then you can always fail back to the known state if you have a big problem.
Ask more questions if you need to.
Brian.