"Earth Angel" and hundreds of other Street Corner Harmony tunes follow a Chord Progression like this In the Key of C:
C-Am-Dm-G7
In BIAB I found a style that fits the genre very well. If you will load 'SLOARPBL Slow Arpeggio 12/8 Blues' into BIAB and then plug in the progression in the first two measures, kill the melody, loop the first two measures and sing along to Earth Angel you will find it fits very well PHILLY. Hope you find joy!