You're quite resourceful Geoff, perhaps you could dig something up
My entire point is that recent advances in image processing due to legitimate machine learning/AI can do such a great job I almost doubt anyone would be able to see the difference between 2K and 4K native images.
Who knows, in a few years we may see all films upscaled to 8k or 16k using machine learning then downscaled back to 4K for the UHD blu and it would be a remarkably better image than just utilizing the 4K master to begin with.