back in the day there used to be some mac guides... osrry can't find the old assembler suite that I had which also had good powerpc refs and more specificall 750(G3) and G4... I'll try looking again later, but it might make a google starting point but with quick search too much fluff from osx and other crap, but also some potentially good powerpc guides... e.g. UM eecs
I'm trying to remember if it was OS9(i.e. "classic") or OSX when I bought it...
Try to fire up my g4 sometime if all else fails and see whats on there...
It was NOT an Apple programmer's workshop assembler/xcode/GNU or anything like that, shareware IIRC or pseudo-commercial(VERY small time).
The G4 was 74xx.
Personally I'd lookup the old apple g3 stuff, and add the IBM/Motorola(freescale) dev dox to the Mac guides... although the IBM dox should be more illuminating as I'm sure the current 750 variant has some upgraded features as alluded to by various wii articles/etc. and as mentioned the other guides as well, general powerpc asm guides...
Powerpc G5 was powerpc 970(IBM)
But also remember powerpc was AIM -> Apple/IBM/Motorola(Freescale now) and more powerpcs were sold to the embedded market than any macs/workstations...