Have not welded up the K-frame, but am installing subframe connectors, and my chassis guy is doing some stiffening work and is putting in an 8 point bar for me, but he fabs his own stuff. I don't mind the car picking up all the drivetrain vibrations if it means avoiding too much movement. The deforming does concern me that you experienced. I'm familiar with the k-frame work, but is it critical?