Do I absolutely have to have new fuel injectors, HPOP, and all new sensors?

What is your question?

I'm having a new 6.0 engine put in my 2004 F-350. I had water in my oil and my mechanic is urging me to replace the HPOP, all fuel injectors, and all sensors. Is this all absolutely necessary. I don't see how these parts could have been damaged, but I'm no mechanic! I know it would be better to do so, but I'm already going to be out almost $13,000.00 and really can't afford an additional $2,500 to $3,000! I need guidance and would greatly appreciate any feedback.