The return springs that came with the Edelbrock progressive linkage were garbage. They were different dia and length. They also had a short heavy pull.
I found some s/s 4" ultra-precision springs from Mcmaster Carr. The spring tension is lighter than the ones from the edelbrock kit and have a better feel. Mcmaster also has the spring pulls
I'm going to order the Inovative LM-2 wideband kit to tune these carbs.