I am curious how this ended up? I will most likely have the same scenario. I will be going from a gpu similair to what you had which was an nvidia to an amd.
Keep in mind you can have almost the exact same color reproduction** between two cards of the competing generation; assuming your using the exact same hardware (specifically the monitor). However, it may require a bit of tweaking and fine-tuning to acquire it.
**Note: I can't say 100% since they are different cards, however you can achieve color reproduction so closely that the naked eye will never notice the difference anyways.