Darren,
If you already have the heads, then yes you will need to get them drilled for the 1/2" studs. If you are getting the heads from Stage V, just let them know and they will do it for you. Also you need to tell them that the heads are for a KB Block as the water holes are slightly different. They can drill the heads for these also. If you already have the heads there is a modification that needs to be done to them so they will work with the KB Block.