@HelpImaRock I definitely don't hear C7/G7. IMHO the original is something like Gmin7add6.
If we call this Gmin13, you find C7 buried inside. So while the Real Book changes are not true to the original...IMHO they are not all that out of line.
Gmin13 (all notes and extensions) = G,Bb,D,F,A,C,E with C7 in bold. Keep in mind C7 is a normal IV chord for G Maj blues.
So while playing C7 does change the mood a bit, IMHO it does not really shift the tonal center away G Maj Blues. Pretty sure this was the whole point behind the original.
IMHO, the choices you make on how to play this song are somewhat dependent on who you are gigging with. Some people will chastise you for playing C7, and others will chastise you for playing it like the original.