Welcome to the Team Chris!
The frame stands for the motor are the same between the SBC and the BBC (that is the stamped steel part that bolts to the car frame). The motor mounts themselves (the factory rubber isolators) are different however between a six banger, a base engine V8, or a high performance V8 (any motor rated above 300 horsepower).
All BBC engines exceeded 300 horsepower which is why the motor mounts for BBC differed from a 283 or 275 horsepower 327.
All Chevy motor frame sands should bolt into the same holes. All Chevy motors, six or V8 used the same frame stands only the motor mounts differed in shape and size.
The differing holes in the frame are for differing engines (Olds, Buick, Pontiac or Cadillac that all used the same frame for a B-body). BOP motors used one set of three holes and Chevy used the other set of three holes that were punched into the frame.