This info came from
GlobalWest
The following cars provide 11 inch brake spindles.
Apollo 1975 GMC Sprint 1973-1977 Pontiac Full Size 1977-1981
Buick Full Size 1977-1981 Grand Prix 1973-1977 Pontiac Lemans 1973-1977
Buick Century 1973-1977 Monte Carlo 1973-1977 Riveria 1977-1978
Camaro 1970-1981 Nova 1974-1979 Seville 1976
Chevelle 1973-1977 Olds Cutlass 1973-1977 Skylark 1975-1979
Chevy Full Size 1977-1981 Omega 1975-1979 Ventura 1975-1977
Firebird 1970-1981 Phoenix 1977-1979
These cars provide 12 inch brake spindles
Buick Full Size- Le Sabre Wagon / Electra Wagon 1977-1994 Cadillac Fleetwood and Deville 1977-1984 // Brougham and Fleetwood 1985-1994 Chevy Full Size 1977-1996 Caprice, Impala, Belair, Biscayne
Olds Delta 88, Delta 88 Wagon and Olds 98 / 1977-1992 Pontiac Full Size Bonneville, Catalina, Grandville 1977-1986
Also if you don't want to go through the hassle
globalwest has kits to go in either 11 inch or 12 inch rotor size
GlobalWest