im pretty sure you dont have to drill the block or whhatever,,thats what the conversion kit is for..
last i though the b16 heads had 4 places for dowels.and theose 4 places are a little smaller than the ls which only has 2 places(a little bigger)
so you take your dowels and put the bigger end down into the block..the thing is that you might need to open the holes on the gasket up a little bit to fit over the bottom of the dowel