I think it's really unlikely that he was a white guy if he won a talent contest at the Uptown Theatre. Also the way he sings on his Cotillion single, plus the lyrics, makes me sceptical of that particular claim. All the other acts on Dionn would appear to be African-Americans and most of the signings came via the Uptown where George and Gilda Woods (famous Philly DJ and his wife who co-owned owned Dionn) hosted the talent shows.
The Woods' were prominent in black life in Philadelphia, including the Civil Rights movement. The idea they would get a white guy to sing "Keep On Striving" seems perverse.