Hi Leandro,
I used Fontlab, a commercial type editing tool, which has a feature to globally change some of the metrics.
If you can decide upon how much you need the letters spaced out, I can revise the ArialSpaced font to suit.
An easy way to experiment with spacing is to use Word, if you have access to it. Using Arial write some characters in, say, 36pt, copy those to a second line, then select all the second line and use the Font Spacing feature to adjust until you get what you need:
When you are happy with the result, let me have the Word document and I’ll modify the font. If you don’t have Word let me know and we can find another way.