Q: it leaves me with a bit of harmonic blue balls when I try to apply it in general.
A: if Emin/G to Cmaj feels too lame and weak, you're gonna want to swap out the mid-range G for F. so you have G bass, then F B E over it. that's G13 but maybe you haven't tried it that way? that can be made crunchier if you also add Ab in there. that might actually remind you of the 1930s. but none of this means anything without the entirety of what else is happening in the song. most songs are not just those 2 notes, no words, etc