for the steering bearing races i always use my home constructed tool made out of 10mm threaded rod ond two pieces of thick plate ar either end.just thread the bar thru the column,fit the two plates,thread the nuts on and tighten until the races pull into place.
as for the crank shaft race,bit of a swine to get off.i usually throw the crank in the freezer for the night!sounds daft,but the shaft metal contracts,the race,being hardened metal dosn’t,thus the race usually drops off with a bit of light force.
if that dosn’t work i take it to the machine shop at work and let the experts remove it!they usually press the new one on for me too,usually costs me a box of tea bags though!money well spent.
the moral of the story is,if you have to apply unnecessary force with a hammer and chisel you are probably doing something wrong.remember the crank is the heart of the engine,any twists snowball through to the rest of the engine causing pounds or euros of damage.
mb development have a good stock of lambretta and vespa specialist tools,as do many of the good scooter shops!
hope that helps