I've converted several from sprint to vzw. Use the helmi wm6 rom pick verizon in all the carriers and you will have to use No Id bootloader to load the rom. However dependant on your bootloader version if its not 1.00 or 1.02 you may have to make the rom with the correct bootloader version then put it in the no id ruu to get around country id error. This is my thread at how to get data working
http://forum.ppcgeeks.com/showthread.php?t=20090. Every one I have converted after writing a vzw prl to it will do a *228. The only hard part of this whole conversion is getting the esn added to the database if it isn't already.