My car shifted exactly like that till a week ago when I re adjusted it. Check out this link. Go to 1971 car and linkage adjustment. I think mine is close to 1/2 play at the rod now. A few tuns of the rod change the shifting of the tranny when you are close. A few trips down the road and you will have it how you want. Kick down in my car now works too.

http://www.imperialclub.com/Repair/Lit/Master/index.htm