Come with me as I take a 20 year step backward in technology...
Parts needed for EFI - Carb conversion:
Low pressure external electric fuel pump. 
Mechanical could be used, but seemed like more work. I purchasd a 4-6psi Carter. Other popular pumps include the Holley Blue and Red
Carburater and intake.
I chose a 600 cfm Carter along with the basic Edelbrock Performer intake.
Duraspark II distributor.
If using a HO engine, you must use a distributor with a steel gear.  I found the cheapest way to do this is by ordering a 1985 GT distributor(only carb'd stang with roller cam) through Autozone. 
$50 if you have a core deposit.
Ignition Box
I just used one I found from a junkyard that was attatched to a Duraspark 2 distributor.  You can however use a GM HEI module in place of an ignition box if you wish.  Also, if you think you may want a MSD or other aftermarket box, now would probaly be a good time to just go ahead and buy/install it.
Here is an excellent detailed description by someone else on how to use the HEI module
Kickdown Cable
The EFI AOD cable will not work with a carb(atleast with not doing alot of work to it). Lokar sells a cable to do this.  Of course if you have a manual tranny, you have nothing to worry about.
I ordered mine through Summit for $51
Ditch the EFI valve covers
The Mustang EFI 5.0s have the PCV on the back of the intake. Since carb intakes dont have that design, youll have buy valve covers that are designed to have breathers/PCV valves on them. Cheapest thing to do is buy tin valve covers at the junkyard from any carbd 302. You can either run one breather on each valve cover, or a breather on one and a PCV on the other.
The fuel pump
Many people use the factory fuel pump relay with their carb'd setup, I on the other hand to the simplest approach.  Ran a + wire from the fuel pump to the closest key-on hot wire I knew of.  That happened to be the one used for the stereo.  Ran the negative wire to the body from inside the trunk.
I chose to mount my fuel pump on the back part of the trunk between the bumper.  I should say though this is not the safest place to have the pump mounted(someone hits back of car...KABOOM)
The goal is to have the fuel pump as low as possible, and as far back as possible.  These types of fuel pumps syphen(sp) terribly, but push excellent.
Also, its not a bad idea to run 2 fuel filters.  One before the pump, and one before the carb.
Ignition Box Wiring
The orange, purple and black wires go directly to the wires of the same colors on the distributor.  The red wire goes to the + side of the coil, while the green wire goes to the negative side of the coil.  The white wire is optional.  I beleive it goes to one of the side terminals on the starter relay.
As far as mounting the box goes, I placed it on the passenger side of the engine bay as you can see in the picture.
Additional wiring for conversion
To use the factory tepmerature and oil pressure gauges you will need to run a couple wires from your front wiring harness(the harness that comes from the driver side of the firewall) Should be two black plugs, or one black and one grey plug.
The temperature gauge wire is red with a white stripe. 
The oil pressure gauge wire is off white with a light pinkish stripe.