Good find! *Welcome. *Just make sure that the pump primes up from a bucket quickly (it should being procom). *If it does not then dont keep working the pump dry and plumb in the water to it instead, even temp for now.
Dont turn on the heating elements until the boiler is full. *I would leave the heating elements off until after you fill and drain the boiler a few times using the bung in the bottom of the boiler to drain it. *Then when all the sediment is out turn on the boiler and see if it come up to speed (make sure the safety valve is still on the machine and has not been tampered with). *Once boiled activate the steam wands and the groups in turn to see that they work. *You probably wont be able to easily test the 3 way valves without a PF. *Make sure that the pressurestat turns on an off every few minutes. *You should see the pressure gauge moving up and down accordingly for the boiler pressure. *if the steam wand(s) is not working then take off the tip and see if it simply blocked.
Apart from that if it is all good, then get some PFs from Coffeeparts, some new (very cheap) group seals and steam wand seals - if it needs the later - *and get ready to rumble.