diesel injection pump?

Hi, I have a 2.2 sri diesel vectra, 2001 reg. I may be about to change my engine for a used replacement one and I am after advice reference the fuel injection pump. My mechanic believes i will need the new diesel pump coded to my car is this true? I went to my local vauxhall dealer, and they believe I should be able to change the whole engine with out having to recode it to my ecu and key. They are 95% sure about this. However my mechanic thinks i will. Has anyone one done this already, and do i need to do it or not, and if so how. Any Help on this issue would be greatly appreciated. Cheers Chris