Only driven the car a couple times since taking it out of storage, but would say there's a marginal, not vast, improvement with the Amsoil vs. motor oil. Cold shifting (mid-50's F) is still stiff for a few minutes, but no 1st -2nd gear crunch.
I think this is as good as it's going to get with this trans. As others have stated, it shifts better at high revs.

I'll be in Dayton mid-June for a road rally, so PM/email me if you want to sched a mutually convenient time to drive my car and draw your own conclusions. Will be at Wright-Patt museum 6/15, which should be close to you.