Lower control arm shaft(some call it a pin) question

1973 Dart here. Do you need to have the full weight of the car on the LCA bushing to tighten the shaft nut to spec? I'm using Energy Suspension polyurethane bushings. I greased them according to instructions. I just want to get it snug but with the car currently in the air the nut reaches a certain point on the threads and the shaft just spins inside the bushing. I understand that the car has to be on the ground for the final torquing.