Some freewheels do wobble due to poor tolerances in the machining operations.
As it shows the same problem with both units, The chain is suspect. Even if it is a new chain is it of the correct type. If no stiff links, is it old, stretched out?
Small chance the jockey wheels are binding.
An even smaller chance that the shift lever needs lubrication, take it apart, verify it is assembled the correct way, lubricate it with grease and put it back together.
Campagnolo downtube shifters of that era are really reliable if lubed and assembled correctly.
If you have braze on shifters, install the ringed screw prior with oil and make sure it threads in completely w/o too much effort.
You want to insure that the resistance you feel upon assembly is from the belvel washer spring and not from the threads.