The 575 and CC logic boards have identical dimensions, and compatible (if not identical) electrical connections on the SCSI only edge connector. The 58X machines had a very similar external case to the other 500 series cases (but not identical - the new non-Trinitron monitors had a different radius tube so the top half of the case was redesigned) and the similar but longer slide-in lobos from the 63X series. The internals were an inch or two further forward (necessitating the surgery you mentioned) and had IDE and SCSI, so a completely different edge connector than the CC through 57Xs.

Unfortunately I can find the 580/630 through 6500 edge connector diagram, but not the CC-57X one.