The bolt pattern and hub/splines are the same. Now if the inside parts that do all the magic work match your motor is a question. If its a converter built for a small block......yes it will bolt up and move, but the stall speed, flash, and multiplication ratio, and slip %might be way off
A chevy converter is not designed for the amount of torque a Buick makes and the rpm range of that torque. A properly designed converter by someone who is familiar with Buick specs will out perform any off the shelf chevy converter.
