I have used the mustangs unlimited kit on 2 older cars I have built. Its pretty straight forward and save alot of time compared to the first time I did it and hacked a 5.0 donor cars harness.

Here is one of the better efi sites as far as how-to goes, it has some decent links on it also.

As for mustang forums and svt stay out of them too many douche bags that dont know ****. If you want a good mustang site as far as vintage stangs go try mustangsandmore.com and hardcore50.com has alot of good people on it.