Ah, so having common problems is a good thing, there tend to be solutions! It's the unique problems that are the real headache.. is this a sign of just age and wear or would changing fluids (even without additives) help?
From what little I have seen underneath, any rubber part I can see is very aged so that'll be the first thing to tackle before looking at the steering box I think
You're right - synchros are bound to start going weak with age, as well as after hundreds of 'Italian' gearchanges! Changing the fluid would definitely help, I've heard good things about Redline oils.
Its defintely a good idea to sort all the tie rods and ball joints before messing with your steering box, as it might indeed be okay after all.
72' Alfa Romeo Giulia Super
68' Lancia Fulvia Rallye