I have a suggestion, just an idea, I hope it might help.
Since there are a number of drivers that require so much computation power that older PPC machines can't simply satisfy, a solution could be to exclude from compilation some drivers in order to mantain the code smaller enough to remain within the limits of the GCC compiler.
That's a terrible idea, and the MAME team is not going to do that.
If one of the goal of MAME project is not only the preservation but also the playability
I'm going to stop you right there and inform you that the goal of the MAME project has never, EVER, EVER
been about "playability" as well as preservation. It has ALWAYS
been about preservation ONLY