Besides compression test, what else to check.

[RonA]

I am getting ready to swap injection pumps to see if it cures my rough idle, low power issues. It was suggested that I do a compression test while I am at it. Any thing else to check for. Motor is 2002 with 34k miles on it. New head,gasket, o-rings, studs. No boost leaks. I want to make sure I don't overlook anything this time, I am even having 2 pumps built so I don't waste a year messing with a bad one again. I can always sell what I don't use.