It depends on what you want to do and how much hp you are after.
Here is one site that talks you through wiring on a 91-93' Mustang. Also has a swap for a auto to a T-5 if need.
http://projecthp.ford23.com
right now I am looking at a block on a site that is a 2.5
http://racerwalsh.zoovy.com/category/4cylinder.shortblocks/ that has a short block for a new build. and with that I would be looking at changing th rear end out and the trans to a 5 spd. I am looking to go turbo but not 300+ I am just looking to get more out a 4 cyl. my pony is riding over 300,000 miles and i am afraid that she is oing to give out on me or at loeast begin to give me troubles. with a new powerplant and a new drive train I believe that I can extend her out for another 15 years. that will give me plenty of time to build up the engine and get everything I need to complete the project.
If I can do the same thing to this block by rebuilding it and adding the turbo then I will do that and soon after change the trans and rear end out.
I am looking for a set of 4 wheel disc brakes, dont care if there 4 lug or 5 really as long as I can find outlaw wheels to go with them.
for me this is a daily driver of over 80 + miles a day so the gas mileage played in the decision not to go over 300 HP I just want to have a good strong Block to begin the project but if like you say if I can do this on the block that I have then I will go ahead and try that.