GM had only one part number for the 231 crank, no different number for the turbo Buick crank, but they did have a specific part number for the Turbo Trans Am crank as it was different with cross-drilled oil feed holes.
There were also different casting numbers on V-6 cranks, so that is not an indicator of turbo or non-turbo cranks.
My opinion is that a 30+ year old cast crank, turbo or non-turbo, is not a good basis for building an engine, especially if performance up-grades are to be added to the build.