Once you jack up the lower control arm up and get the weight off the upper control arm with the tire off, the upper control arm should move around pretty easy. Looks like the metal outer shell is still in the control arm, so you should be able to tap the bushing back in fairly easy. If not you can get some threaded rod, screw it into the shaft and use a nut and fender washer to pull it back in place, just make sure you have the bolt and washer on the other end of the shaft.

Hope it goes back together easy for you.
Just yesterday we noticed on my son's 68 Nova that all his alinement shims came out on one of the bolts and making a popping noise.
I guess we need to check all the frontend bolts every now and then on these old cars.