ACAtune requires Kick2.0 or higher to run.
The ACA630 auto-configs it's memory using Z3 autoconfig. This is not available under kick1.3, so the (virtual) Z3 card is ignored by kick1.3. The system starts up, but does not see any additional memory. You can use addmem to add the 32M of the ACA630 (starting at 0x4000.0000) and run a HD-less computer with lots of spare memory.
Making a Frankenstein Kickstart 1.3 with scsi.device won't really help, as you would only want to use kick1.3 for backwards-compatibility with old software that does absolute jumps into the rom. You should not change *anything* on such a rom, otherwise you risk going incompatible, which is the opposite of what you want to achieve. It would not even be a "because we can"-thing.
Instead of a Frankenstein 1.3, I'd suggest looking into the kick1.4 that came with the early 16MHz A3000's. It might have a place for scsi.device and it might also have an expansion lib that can do Z3 autoconfig. The funny thing about that kick is that you hardly ever get to see the window design, and if you do (with a bad boot HD on the A3000), it really looks like an Amiga from a parallel universe - *this* would be some fun on ACA630, as it supports loading kickstart from a file :-)