Sorry, I missed your question.
Here is how I am used to deal with matte-painting, Photoshop and ACES:
- Let’s say I have an ACEScg render that I want to paint over in Photoshop.
- I would convert it to ACEScct in Nuke and then import it to Photoshop.
- In Photoshop, I would use a “color lookup” layer to load my “Display” LUT.
- At exporting from Photoshop, I would disable this layer and import back in Nuke as ACEScct.
I described this workflow more extensively here.
You could grade it to get closer to your final result, rather than inverting the Output Transform.
Regards,
Chris