So if I find a camero/firebird with a gear going from 3.35 to .68 NWC an I take it apart and install it in my S-10 case
I think what would work best would be to swap the S10 tail housing ONTO the Camaro case.
The gear set you mention sounds more like they are from a Mustang T5.
The answer to your question is this - World Class gears must go inside a World Class case. Non-world class need to go in a non-world class case.
The S10 T5 is World Class starting in 1993. However, 1993 is the only year that the S10 has both a World Class case and a Muncie pattern where it bolts to the bell. 1994 and up are also world class but have a Ford pattern case.
The Camaro T5 is World Class from 1988 - 1992. 1993 and up Camaro T5s are also world class but have a FORD pattern case.
Find a nice Camaro or S10 T5 with gears you like and with a Muncie case. If it's a Camaro T5, just swap the tail housing to S10.