Movement does not equate to worn out, and the nut stops on the metal tube so that's where it's supposed to be.
But I admit that on a 68 car, those bushings could be ancient. and if they are, then so might be any and or all the other ones as well....... especially the LCA inner one.
Since you have to take the LCAs off anyway, to install new the strut rod bushings, you might as well have a look at them now, before ordering parts.. and then you might notice that the idler arm is flopping around, and the lower bump-stops, if still there, are rotten ...... and then you remember how wishy-washy those weakazz 318 T-bars were, not to mention the 56yo shocks; and so, before you know it, your strutrod bushing job has snowballed into nearly two-grand, just ........ like ....... that...... lol.