66 mustang EFI
 

what is the simplest way to convery my 302 to fuel injection?

The easiest way would be to take the whole EFI rig off a 89-93 5.0 and swap it for the carb/manifold. If you take this route, you need to make sure that you get ALL of the EFI componants, including the computer, o2 sensors etc.
Theres a bunch of websites out there, heres 3 examples.
http://users.ev1.net/~gbuzek/index.htm
http://www.ultrastang.com/Ultrainfo.asp?Page_ID=1
http://www.windsorfox.com/

It's the easiest way and also the cheapest because you can get most if not all from a junkyard. Most other EFI kits have to be bought brand new.