*checks MacTracker* Yes, it would appear that 7.1.2 was the first OS for the PowerPCs, shipping with the 6100, 7100 and 8100. I can't really imagine seeing System 7.1 on a PowerPC though! (I always associate System 7 with 68ks, especially the pre-7.5 ones as you usually only see those versions on LCs and things, not normally even on newer 68ks let alone Power Macs!)
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Main system: custom C2D 2.66GHz tower/4GB RAM/2600XT 512 MB/500GB HD/XP Pro x86+Vista Business x64
Main Mac: Beige G3 minitower (Sonnet G4 500MHz/640 MB DVD/USB/Radeon 32 MB/OS 9.2.2+10.4.11)