Can a new PDC replicate with existing BDC

I need to repartition my W2K which is PDC and of course I have created IDR for it. I need to have a backup plan in case the IDR restoration failed. Therefore, I plan to manually reinstall the drivers, OS and promote it into PDC, and configure the AD sites and services in order it can synchronize the AD and group policy with the existing BDC (W2K3). My question is, can the synchronization be done with that way?

The way of demoting a PDC to BDC is to change the PolSrvRo registry under HKEY_LOCAL_MACHINE\SECURITY\Policy from 3 to 2. Unfortunately, the PolSrvRo is not found. Do I have to create a key with the same name and add a value for it?

Any help would be greatly appreciated.