Sorry, OS4 is completely PPC only. A very small amount of code will be ran through a 68k JIT emulator, but all the main stuff (including the entire kernel) is PPC native - and won't run under any emulator, as no Amiga emulator supports PPC.
I don't know much about MacOS, but they made the jump from 68k to PPC a long time ago, when the 040 was pretty fast - nowadays it cannot match current PPC hardware in any way.
