An important consideration is that many commercial lever machines DO NOT use heat exchangers. That means brew water is at boiler temp. I believe that the Arduino machines use the same heat exchanger as the rest of the Simonelli lineup.
Don't forget the Kees machines :).
The ones you've mentioned all use 58mm baskets.
Don't get a gas fired machine unless you are running a cart.
Any of your friendly neighborhood Nuova Simonelli or Rancilio dealers could set you up with a machine, parts, and support for these machines. I think if you thought really hard you could find, erhmm, someone, to hook you up... even if they were, say, 3-1/2 hours or so away.
Does that help?