A 2.2mm shift in the mounting hole dropped the SPU I have right into place for Baerwald geometry. While I thought the sound was great with it off by the 2.2MM (I know I said 5 but I was wrong in the end) it turns out that it's better properly aligned.
I didn't really notice because even improperly aligned, the new 401 w/SPU is so much better than my old setup!