Try Funky Nassau, The Meters, the Counts, early Commodores (from the 70s), Tower of Power, Graham Central Station, (most of these are a combo of funk and soul with horns) as well as the Five Stairsteps, Freda Payne, James Brown, Jr Walker, the Stylistics and Martha Reeves and the Vandellas just to name a few for the more sounful stuff you are referring to.
It's a Soul Thang
My son and I have been on a now extended Soul music kick. Late 60's-mid 70's stuff, after some of the artists evolved from pop, before a lot of artists turned to disco, and way before what is now consider R&B. You know, Al Green, Aretha, Stevie, Gaye, Withers, Billy Paul, Mayfield, Temptations, Spinners..etc. Looking for some of the perhaps less obvious choices that folks enjoy that they'd like to suggest for fleshing out and expanding our collections! Thanks.