2> Deploy a new IP scheme on a logically different network outside the private address range. Setup multiple routers to handle the bandwidth load of 250 workstations accessing 20 servers, so the migration can be completed in stages.
Yup, I guest the first option does it well. However, if you choose option 2, you can use 10.x.x.x /255.0.0.0 range or 172.16.x.x - 172.31.x.x /255.240.0.0 range. These 2 ranges are also private.
