If you don't have issues printing jpg then my suggestion would be to try and print the pdf as an image
http://helpx.adobe.com/acrobat/kb/quick-fix-print-pdf-image.html
You can also get the letter pretty much any size you want in inkscape. After you type what you want using the 144 pt just select the letter (select and transform objects) and drag to make it the size you are looking for.