Look at the AFC housing towards the back of the pump (right next to the fuel shutoff solenoid) to see if he has messed with the fuel plate or AFC housing any. There should be a rounded over "security" bolt on the front passenger side of the AFC housing.
I always check all the filters (dont take them off except the air filter) see if they looked like they've been changed lately. I look at the air filter to see how dirty it is, usually a good sign as to how well the motor was cared for.
Nathan
Oh, I always take a buddy with me to look at a truck, they sometimes catch stuff ya don't see.