Unless the label has been destroyed there should be one with a lot of information that may be helpful to the parts guys. The VIN probably will not help because it can identify when the car was assembled, but the engine was assembled some time before that.
The parts guy should be able to tell you where the label is on the engine and what part of the label he needs the information from. If he can't look at the valve covers. When you find the label, copy all of what is there and take it into the parts guy and he should find what he needs.