I built one of those a while back. I first used a regular 60% case, and while it "fit", I never got the pcb to sit properly in the case, even after some filing and sanding. I think I need to drill out more of the case standoffs for it to sit right. it's doable, but requires some work.
but about that time, I got a 3d printer and printed my own case:
https://i.imgur.com/zs3p4GN.jpgAlso, I don't think you want an Alps plate if you aren't using Matias/alps switches. you need a plate to fit MX switches if you want to use the pandas.