I don't think that there is a problem for mounting an ACA630 over an 68010.
Since the 68010 is modded to the mobo, you should check how good the person that did the mod soldered the 68010 in place. The only problem is IF ACA would clip over the 68010 due to bad soldering.
I didn't know about 2 methods of piggybacking RAM to A600. I only knew one but I'm definitely unfamiliar if the mod interferes with the actual expansion port.
I guess contacting Jens Schoenfeld through his website would solve your mystery.