I can't remember a time I have had to lift my suitcase over my head on a train. My favorite places to store my luggage are between the seats where the backs face each other for the 4 tops of tables, though maybe those are going by the wayside? If not, the luggage racks at the ends of the cars (and I have seen a few in the middle?) are nowhere close to being over your head, more like elbow to shoulder height?
I haven't studied the luggage racks in the first class cars, but since they are more expensive, unless its a sold out train, more people opt for the cheaper ticket, leaving less people in comparison to the 2nd class cars, hence possibly more room for you.
For a personal note, I have been to Italy twice for 16 days each and I have wanted to chuck my carry on sized luggage off of the train it was so cumbersome and annoying to "lug" around wherever I was going.....I would want to punch everyone around if I had to lug TWO suitcases ANYWHERE. I stayed in apartments with washers that we did laundry halfway through to cut down on luggage. Is that an option for you? A carry on sized suitcase (I check that sucker as I hate lugging it around, so not recommending the necessity to keep it with you on the journey over) and a messenger bag or backpack would be WAY easier to take all your stuff onto trains.