Migration from SLC500 to Control Logix

We have a project that is running on a SLC500 PLC. We are planning to replace the SLC500 PLC with a Control Logix. we will have only 3 days to do the replacement, so i problbly need to start ahead to retag the project. But we want the project to work with the SLC until we shutdown the machine. What would be the best way to migrate the project to the new PLC? Copy the project to a test server? is there a way to retag everything quickly?

How are you getting the tags from the new PLC? via the Allen Bradley drivers, or through a 3rd party OPC like Kepware?

Are you able to connect to the new PLC before the upgrade, on a temporary connection? That way you could build everything you need and have it in place

Yes i can setup the new PLC to read the tags but i dont want to lose the functionality of the current PLC until the last minutes. Thats why i think i need to copy the project and retags everyting on the copy.

Set up a test Ignition gateway (trial license). Export the affected tags from the current server and import them into your test server. Maintaining the folder structure and tag names. Set up the Logix driver on the new server and get all the tags’ OPC items converted without the outage pressure. When they all work, export the updated tags (just the tags that needed updating). During your outage, create the matching Logix device in the production gateway and then import the updated tags. They will replace the originals. Twiddle your thumbs for the remaining 71.5 hours. (: