Hi-Towers working on a conversion kit for HP 9mm Carbine. Have to say it's bad ass.
Tough choice if the price is going to be the same as the rifle. Hell you could buy another caliber.. Although very inexpensive Bullpup.
What yas think
Edited to remove pic of wrong conversion kit, add correct one. And add link http://www.hightowerarmory.com/SearchResults.asp?Cat=1829