Managed to find an Alps K-Series that is 10k linear. Holy moly it's big (100mm)!
Even though the 60mm Alps enclosure is only a touch longer than the 45mm, I have lined up the throws so you can see where they all end up.
I wonder if *over double* the throw of the 45mm is too much, but if I'm gonna go in for a penny, may as well go in for a pound...
I have to say that even with the generic lube/grease on it, the 100mm Alps feels quite nice. If I rock the enclosure back and forth the fader will go from edge-to-edge. Will take it apart and clean/lube it with some proper fader lube, but I'm hopeful.