Just saying a 89 - 93 is going to be easy for you to do and make it work with smog. I have a 97 so add in ODBII and I am screwed. You will have no problems as there is so much for a 5.0 versus a 4.6 I scrapped my 4.6 for a 5.0 and decided I will figure a way around smog some day.
Here is the wiring harness for the 5.0, now find one for a 4.6 that is as easy, good luck
http://www.painlessperformance.com/webcatalog/largeview.php?SearchField=60510