Glad to hear that the oil pressure was resolved, it would be nice to know what the problem was.
Given that this is a new crate engine it would be good to know if the water pump is the correct one for the belt setup. They make water pumps for both rotations primarily to deal with the difference between v-belt and serpentine belts routings that result in the pump running opposite. If somehow he got the wrong pump for his belt setup the pump would be running backward and therefore not flowing much coolant.
Does he have the right fuel pump pressure for the throttle body injection system? Low fuel pressure can result in a lean condition that would be more evident when under load, like going up hill.
The vacuum guage being "0" could be where he plugged it in, throttle bodies don't have a lot of excess vacuum ports like carburetors tend to have. If the vacuum is really zero he has a massive intake leak which would also result in a lean condition and engine over heating.
