Transcode the client's plates to EXR, rebuild the script in Nuke 13+, and deliver back to them as flattened EXRs. Don't comp in V6 if you don't have to.
While The Foundry is currently on version 15 (or 16), the visual effects industry has a long memory. Studios keep old versions alive for legal delivery requirements and asset libraries. Nuke V6 Client
Let’s be honest: If you are reading this, you probably aren't choosing to use Nuke V6 because you love the retro UI. You are using it because a major client sent over a “Nuke V6 Client” package, or you are deep in the archives trying to resurrect a 15-year-old film project. Transcode the client's plates to EXR, rebuild the