Well here's something that might be of help for anybody else getting ready to do this project. A buddy of mine decided to stuff a 5.4l 3v into his 03 Mustang. This sparkplug breaking off thing happened to us too. Here's an article that should help with anyone doing future work.
http://grufmanbil.se/webshop/mektips/tsb08-07-06.pdf
http://grufmanbil.se/webshop/mektips/tsb08-07-06.pdf