When to Weld in Frame connectors

I finally got my Cuda in the garage. I would like to start pulling it all apart to start restoring it. I was thinking that before I pull apart the car would it be a good idea to weld in some frame connectors? Car has no engine or trans. Or should I wait until I am reassembling the car to weld them in?

The garage floor isn't level. So I was going to level it up on jack stands under the rear axle and under the front control arms. Then weld in the connectors.