NT4 migration to 2003 Active Directory

I’m doing an upgrade inplace from NT4 to 2003 AD. My plan is to load AD on DC1 to include DNS to create the forest. Then add DC2 to the single domain within the forest.
After the upgrade, with the 4 gig NT4 limitation, I’ll have to transfer the 5 master roles to DC2 then remove AD from DC1 then run dcpromo again to rebuild DC1.
I know I’ll loose my original DNS load but will I be able to reload dns again while rebuilding DC1 back with a bigger sysvol? What kind of problems could I encounter using this technique?
Thanks in advance.