Now, I don't know about font width. This is either how many pixels wide a letter is, or how long the entire font is in total.
The largest letter I can see is the arrow and it has a width of 8 px. Try putting in 8 for the FontWidths. If that doesn't work, look at another game's ini sections and try what is labeled there. If it is an offset, find out what that offset is and find an equivilant one in FireRed.
By the way, in the tut, he is fixing the image simply by moveing the two halves of the letters together. The top and bottoms are split apart, so it makes it easier to edit if you out them back together.
Just checking on the intro thing; you did see Knizz's post in R&D, correct?
Edit: Also give 12 a try for the width. I just saw somthing that said GBA 12x12 font, might be what you are looking for.
Awww.... Looks like it need an offset. By the way, how do I look for the offset's equivalent in FireRed? The actual FontWidth offset is from Ruby: &H1E6594.