Sparks was at his best playing a muscular, groovy rhythm guitar behind organists like Leon Spencer and Charles Earland, breaking out occasionally with a melodic, groovy solo. He was a mainstay at Prestige during the '70s, where he was a first-call session guitarist noted for his pulsating twangy feel.
Two of my favorite albums featuring Sparks are Leon Spencer's Louisiana Slim (1971) and Charles Earland's Infant Eyes (1978).
Here's Leon Spencer on Mercy, Mercy Me with Sparks keeping jazz-soul time.
And here's Charles Earland's Thang from 1978 off of Infant Eyes, with Sparks running a string-bending solo. Also on the date: Bill Hardman (tp), Frank Wess (fl,ts), Mack Goldsbury Melvin Sparks, Grady Tate (d) and Lawrence Killian (perc).