With no hardware in sight why not emulation or virtualisation? If I was clever enough I would create such a program (unfortuanally I only know how to emulate a 6502A ;-) ).
I see two ways this could be done (with expertise and time from people),
One way is to emulation with x86's. There could be a Virtual A1 program or a UAE modification that emulates a PPC accelerator. Sounds slow but I would'nt be surprised if a Core 2 Duo could emulate a 600MH G3 faster than the real thing. I would like to hear from x86 Mac's using Rosetta if this realistic or not.
The otherway is virtualisation on a older PPC Mac. The processors are the same, and I find virtualisation 80% speed of the host as long as I don't try and do 3D graphics on it.