What ever you do dont flash the Sprint update. It will program the radio for sprint settings. Even though you may still be able to make and recieve calls afterwards, data wont work, *228 wont work, not sure about voicemail. Its a pain to fix. I learned the hard way.
DCD ripped out the radio update into a standalone update. This is where you wanna look to get the updated Radio ROM.
http://forum.xda-developers.com/showthread.php?t=376012
There are good instructions in the first post for the order you should do things
Then look at No2Chem or DCD's 6.1 roms for vzw and choose one. Ur gonna have to read alot. You'll see that my post count is low because I lurk the forums a little to much. Gotta read everything, its the only way. Then you'll see all the other problems people run into and you'll be able to swing it. Read the guide to flashing sticky at the top of the forums.