you'll be alright dude, i recently put a new engine in my car and was thinking the same thing, but once u get going, everything is reasonably straight forward...
when u first look at the engine bay you'll probably think to yourself 'what an abortion', but if u either tag or mark individual groups of bolts to nuts and threads, or video your work you should be sweet, and most of the wiring and clips will sit fairly steady in their original positions if u know what i mean...