Replying to Boot-binding compatibility between different K2/Full Tilt shells.

I found some used K2 FL3X Revolver Pros (classic Full Tilt boot style) for cheap and was looking at reselling them. However, if they are compatible with my current bindings, I may just stow them or my current Full Tilt Descendent 8 ski boots for the future.

Both pairs of boots are the same size and have ISO 5355 soles. They do have different shells (Descendent vs. the classic full tilt shell style), but, considering that they are made by the same company with K2 absorbing Full Tilt into their own line, would it be safe to simply click the Revolvers into my bindings mounted for the Descendents?

Second question(s): The Revolver Pros clearly have been used a bit, but it's only January, and they are a 2022-2023 boot. They felt comfortable trying them on, but would it be worth going to get a heat mold when the liner has already been packed in by someone else? Liners seem to be $100-$200, but is it sometimes worth getting a fresh liner?