Peter, just back from hours and hours of reviewing old gospel stuff (and I mean OLD, some from the "Fort" music documented at American Memory). I think that what you are looking for is in the organ part of these old classics. I'm hearing distinct doo-woppy harmonies, mouth music, and rhythms in the organ accompaniment, as well as in the boogie-woogie walking-bass piano parts.... That doo wop sound is mouth music standing in for all that texture. And the harmonies in doo wop seem to me to have been lifted from the gospel sound (no pay in gospel to speak of), and just secularized. IMO, the nonsense syllables of doo wop serve in place of these instruments and the interjected religious-fervor utterances. And then of course the white doo wop groups would have tagged on from there-- not the first time white folk borrowed a little black soul to spice up the joint.

I could send you a disc with some MP3's.

~S~