Are you using any migration tool for this?, if not what are the major components in this migration? (1. All revision or Latest revision, 2. File Types, 3. Any Legacy Data, 4. Revision specific or configuration specific repeationship, etc).
In General Migration from one system to another system will be carried out by offline. Once all the data get migrated an update migration (Delta Migraion) will be done for the affected file during the full migration process. The approximate time required to do the Delta migration will be 2 day (Done in Weekend), it may varry based on the affected file size.
7 Days for 120K files seems a bit excessive....
Lots of companies do it over 3 day weekends, schedule training, have people work off line, storing files on their local disks, update procedure documents, best practice documents, play songs and games....
Ask if you can at least still have read only access to the DBWorks database, that will be very handy.