RaRa

Im thinking about buying a 05 chn613 it has 2 mill miles. The engine has been rebuilt twice about 400k on rebuild. It has the e7 460. Is the e7 460 from 2005 a good engine? How many times can this engine be rebuilt? I went and looked at the truck it is in excellent condition inside and out its a one owner. I basically want to learn as much as I can about this engine, I cant find that much info on it. Common issues etc.