Bare minimum for an LS swap?

[T/A Addict]

I haven't scored a replacement motor for the ill Chevy 350 that is currently in my '69 Firebird and haven't set my mind yet on type of replacement - another cheap used Chevy 350 - a Poncho 350,400,455 - or my first LS swap. My main objective is just to get it running this spring as cheap and as comfortably as possible to enjoy while I finish my other project.

With that being said if I can pick up a complete 5.3 with harness, ecm and accessories what are some of the items at a minimum that I would be looking at having to purchase to complete the process? I want to use the info to compare costs of either direction.