I have had to replace my ignition assembly also. I bought mine from Rock Auto for like $10 with the chrome outer piece. Find yourself an old school experienced locksmith and he should be able to reset your ignition tumbler to match your existing key. That way you don't have to mess with your door locks. In my case, I had no original key so I had to match the door locks to the new key which came with the new ignition switch. My locksmith said he could go either way with the re-keying.
Not sure if originally Ford had separate keys... doors vs ignition, but now I have one key for both. Which is a bit more convenient. My truck is a '94.