If your only solution is emulation, you can try to virtualise a linux distro too. I don't know
what is the most effective and efficient: to emulate a power pc to run an old Mac OS, or to virtualise a modern linux distro on your intel processor.
For CPU stuff the virtualisation will be probably a better choice, but for GPU tasks, I don't know what SheepShaver does, and which virtualisation system for mac is better.
Since there is some free virtualisation system (like virtualbox) and there is plenty of free linux distros, it cost nothing to try (only the time spent).