Just FYI to anyone interested, embedded fonts in side loaded KF8 books will work on the Kindle Fire HD but there are exceptions.

If the embedded font is referenced only within the BODY tag, the font will display on most eInk Kindles and K4PC. This method also works for ePubs. However, it will NOT display on the Kindle Fire HD. I'm not sure which tags will work and which won't, but I did get it to work by referencing the embedded font(s) in a Class and assigning that Class to a P tag.