5.7 ecu/wiring

For the 5.7 swap I'm working on I still need an engine harness and the ecu. I plan to get one from the junkyard yard. anything I need to know before I do and is there anything else I might need to pull with those thing? Got a 2005 5.7 from a truck with a 727 trans. I'm not super familiar with this stuff so any help or knowledge is appreciated.