All A body Lower Control Arm shafts interchange from the 1962-1976 cars.
The earlier years used the style ball style machining on the shaft, and the later years were round diameter.
The only other minor difference if the shaft used a castle nut, on the threaded portion of the shaft, then a hole was drilled for a cotter pin.
The one without the drilled hole is for a lock nut type of fastening nut.
You haven't removed the bushing "shell" that's left on the shaft.
Your not getting the torsion bar in, has got Nothing to do with a bushing on a lower control arm shaft.
The steel bushing left over from the old part is still on the shaft. Remove that and it’s normal again
but that bulge looks funky. Ebody maybe?!?2View attachment 1716281229