Through the magic of the encyclopedia lifetime batting and pitching registers.
Note that my changes/additions are in bold.
C: Elston Howard (61-64)
1B: Moose Skorown (61-65) or Mickey Mantle 65-67 (and first two weeks of 68 - appeared in 15 games for the Gamblers that year)
2B: Cookie Rojas (64-67)
3B: Harmon Killebrew (61-69)
SS: Rico Petrocelli (65-69)
LF: Rico Carty (64-69)
CF: Curt Flooyd (61-67)
RF: Wes Covington (65-66)

SP1: Jim Kaat (61-69)
SP2: Gaylord Perry (64-67)
SP3: Mel Stottlemyre (64-69)
SP4: Mike Cuellar (66)
SP5: Larry Jackson (61-67) Also played about half of 1968 with the Gamblers.

RP: Moe Drawbosky (63-68 Started 68 with Gamblers then traded to Gold Sox)
RP: Ken Tatum (69)