Interesting. I could test it out here if I could find a 15.5mm spacer, since I already have the PicoPSU. I'll see if I can find / make one. I mean it really is a tight fit now, and I feel like I'd be forcing the screws into place, but 1.5mm smaller, it may just have enough clearance to fit right.
I should get a spacer/mount for the CT60e anyhow, before I transfer it over to the wizztronics case.
Atari 8Bits: 800xl, 600xl, XEGS, 800, 130xe, 130xe (VBXE, U1MB, Stereo POKEY)
Atari STs: 1040STf (broken shifter), 1040STe, Mega STe, TT030, Falcon (CT60e, SuperVidel)