Remove and Rejoin Computer to Domain Consequences???

I have many GPO's in my AD that have run based on the computers Delegation rights.  In other words, let's say I have (1) computer based policy for a container that includes 300 computers.  On 5 of the computers I do not want the policy to run so I add those 5 computers to a security group and in turn remove that group from the "read" and "apply group policy" security rights of the policy.

My question is this....If I remove one of those specific (5) computers from the Domain before reimaging it, and then rejoin it to the domain with the exact same computer name - will I have to re-add it to the security group and it was in before I unjoined it?

Do I even have to unjoin the computer before reimaging it or can I just reimage it and name it the same after reimaging and it will pick up all of the rights and be placed in the same container it was before I reimaged?

This is a confusing question, so please respond with clarification question if need be.

Thanks in advance!