I managed to get my hands on a new Tex case the other day. I would imagine it's the same ones that MK will be selling soon.
The plates sold by MK do fit inside the case, however, I feel like the case was designed for the Filco plate... possibly the majestouch 2 only. as the case has slots on the top and bottom for the metal tabs to go into to prevent the plate from moving around.
There are no screws to fasten the keyboard's switch plate to the case. The plate sits on a ledge inside the bottom portion of the case. If its flush enough, or has the aforementioned tabs, it won't move. Because the MK plate doesn't have those tabs and is too small... the plate does move around in the case. It may not be a huge problem.. but it is something to keep in mind.
I haven't received all the parts to finish my board yet... but when I do I'll be sure to update everyone on if it was a problem.
Here's some pics:
Whole case.. two pieces.
Pic without the plate... see the notches?
Pic with MK's switch plate inside the case (note the space for it to move)