Replace every piece of rubber. No matter what they look like. Fifty year old rubber will be useless. Start with the torsion bar, engine and transmission. When changing the transmission mount also replace the flex disk. Replacing this rubber should eliminate the vibration.
Then take a serious look at the kingpins and the upper and lower control arms (there could be some serious wear that should be addressed). Have the alignment shop test the condition of the king pins. The control arm wear will be difficult to detect because of the tensison from the main springs. Check the grease nipples and the rubber seals on the pivot points.
The rubber mounts on the front springs will also be hard and inflexible and should also be replaced.
I had a catastrophic front end suspension failure a few years back. I completely rebuilt everything and it blew me away how well the car handled when I was done.
Good Luck

__________________
Britton McIntyre

68 280 SE coupe 'Hairball'
70 280 SL
71 280 SEL - RIP May 2010