ok, so I have a B16 complete head. I have a B18B block with rods and pistons. I went to the machine shop last night with a friend asking about how much it would cost to put the head on the flow bench and make sure that the seals are good and no valves are bent. He said that I should bring my block too to make sure that the valves are not going to hit the pistons and that they will clear the little dimple in the piston. Do you think that this is a must? You see people all the time just slapping on a GsR head or B16 head and it works fine.

 

If its a stock head (stock valves) then I dont think you need to worry about piston/valve clearance with an LS bottom end.