Chevrolet's power-team charts show the lower-compression, lower-output engine range that prepared the car for lower-lead fuel. The Z28 LT-1 is listed at 330 hp gross/275 hp net and the nominal “396” big-block at 300 gross/260 net, demonstrating why gross and net figures must not be compared without labels.
RS, SS, and Z28 remained distinct choices; the factory sheets are the correct starting point for determining which combinations were orderable.