In case anyone is interested, the SMK65 PCB from lfkeyboards does indeed fit in this case. I have one it it right now. Also, it works with the included plate. So, if you want to put 2nd gen SMK swithces in your M65-A, you're in luck.
http://www.lfkeyboards.com/smk65.htmlI did some very very minimal sanding on the top edge of the PCB where the two posts inside the case made contact (the ones that come down to meet the bottom for screws). I might have removed 1-2mm but no more.
The connections is micro USB, but it fits and I have no trouble plugging in my usb cable.
I'm just not 100% sure I like the switches in this case. I adore the sound and feel of these switches in my Siig minitoch, but they are not quite the same in this case. They sound higher pitched and lack depth in comparison. I'll have to sit on it few a weeks or so to decide.
A note about the PCB. The owner of lfkeyboards has been a swell dude and very responsive to my emails. He forgot to add the Piezo speaker on my board and is sending me a new board to fix the issue. That's pretty nice customer service! The current revision of this PCB has issues with the first 3 underglow leds as you can see here.
The new one he's working on for me will fix the issue by running jumper wires to make them work. He plans to fix this in a new revision soon.
Also, since I've only tested the PCB with tweezers (shorting), I have no idea how well it will hold up or how easy it is to program. But it looks top notch to me and it runs QMK.
https://github.com/qmk/qmk_firmware/tree/master/keyboards/lfkeyboards/smk65