The Vega steering box is not recommended for cars that exceed 3000lbs in weight and that also wheel stand.
Borgeson sells a better steering box and you can use your current steering shaft.
https://www.borgeson.com/78-88-Malibu-82-92-Camaro.html
They also have a replacement steering shaft.
https://www.borgeson.com/G-Body-F-Bo...ing-Shaft.html