Referring to Mr Fanatic's
A Visual Guide To New English Library: Volume One we find (most of) these:
Alston Anderson - The Slave (June 1968)
Lionel Webb - Sparhawk (Dec. 1969)
Harold Courlander - The African (1970)
Joseph Chadwick - Black Velvet (Sept 1970)
Robert J. Hensler - Mantee (1971; Paperback Library, 1969)
Leslie Gladston - Slaver (May 1971)
Leslie Gladson - King's Slaves (July 1971)
Robert Tralins - Black Pirate (Oct 1971)
Robert Vaughan - Mistress Of The Lash (Nov 1971)
Stuart Jason - Black Lord (1972)
Stuart Jason - Black Prince (1972)
Stuart Jason - Black Emperor (1972)
Leslie Gladson - The Abolitionist (1972)
Clint Rockman (Ken Bulmer) - Black Slaver (May 1972)
Clint Rockman - Black Queen (June 1972)
Clint Rockman - Black Gold (Sept. 1972)
Clint Rockman - Black Ivory (Nov 1972)
Robert Tralins - Rampage (Feb 1973: 1st published as
Runaway Slave, Lancer 1969)
Robert Tralins - Slave's Revenge (1973)
Robert Tralins - Black Stud (March 1973: 1st published as
Black Brute, Lancer 1969))
Clint Rockman - Sable Diana (Apr 1973)
Adam Turner - Voodoo Queen (May 1973)
Norman Daniels - Slave Rebellion (June 1973)
Jeffrey Lord (Michael Avallone) - Jeb (Sept 1973)
Mark Swanson - Fury (Sept 1973)
Norman Daniels - Jubal (Oct 1973)
Clint Rockman - Sable Adventure (Feb 1974)
Clint Rockman - Sable Mistress (Sept 1974)
Robert Tralins - Black Roots (omnibus of
Black Stud,
Rampage and
Slave's Revenge,April, 1977)
Kenneth Roberts - Black Fire (June 1978)
Robert Blake (James Moffat) - Black Reaper (Sept. 1978)
Clint Rockman - Sable Ivory (omnibus of
Black Ivory and
Sable Mistress, Jan 1979)
Robert Blake - Black Summer (Feb. 1979)
Stuart Jason - Black Lust (June 1979)
L. A. Grenville - Generation Of Blood (Oct 1979)
Robert Blake - Black Fury (Dec. 1979)
Leo Callan - Black Sapphire (Feb 1980)
Robert Tralins - Panther John (May 1980: Lancer, 1970)
Robert Tralins - Chains (Jan. 1981)
Leo Callan - Black Rebel (Oct. 1981)
Leo Callan - Black Sapphire/ Black Temptress (Nov 1981)
Perhaps a Vault regular or two will be kind enough to flesh it out?