first things first i got a b18a and a b18b head, i heard the b18b head is less restrictive than the a head, i am going to have a good port, polish, and valve job done it one of the heads, and then put that back onto my block, also doing cams. would it really matter what head i port and polish out?

also am doing a new bottom end, want to know what it would take to put in a b20 block with the b18 head on it? any special head gasket? or would a b20 head gasket work?