Thanks for that link.

I've found the following records Watkins was on, but no substantive info otherwise. Mostly via 45worlds.com and Discogs, though Coleman 5997 is also currently for sale on eBay for $24. I may buy that.

Singles:
Coleman Records 5997 (1948), UP IN MY HEAVENLY HOME (W. Bell) / ONE MOMENT IN GOD'S KINGDOM.
Coleman Records 6009, Charles Watkins and the Golden Melodeers DOWN ON MY KNEES / CLINGING
Coleman Records 6012, LAST MILE OF THE WAY / BLESSETH QUIETNESS
Coleman Records 6013, LORD BE WITH ME (Watkins, Bell) / YES IT'S MINE (Watkins, Bell)
Regent 189 (1951), Charles Watkins CHRISTMAS MORN (Watkins, Bell) / The Meltones WHITE CHRISTMAS (Irving Berlin)
Savoy 4029 (1951), CHRISTMAS MORN (Watkins, Bell) / I MUST TELL JESUS
Savoy 4049 (1954), Charles Watkins with The Original Concertones DON'T LET THIS HARVEST PASS / RUN, RUN AND TELL HIM
Savoy 4054, Charles Watkins with The Original Concertones ?SWEET HOUR OF PRAYER / WHAT HE DONE FOR ME
Savoy 4186 (1963), Charles Watkins and The Pentecostal Mass Choir (of Chicago, IL) SHADY GREEN PASTURES / HEARTACHES

He also had a pretty length recording career, releasing several LPs from the 1960s-80s.

As for the Golden Melodeers, it appears as if the flip side to HE KNOWS MY HEART was I'M BOUND FOR HIGHER GROUND (via click), however, no catalog number. It was re-released on Pewburner 566, 566 Gospel Quartet Collection, Vol. 4.