Could someone explain the differences between the combustion chambers on heads available on 320's? How many different heads were available? I've searched the archives and couldn't find the answers I need. I've found a 320i in a junkyard with a really good block, that looks recently rebuilt, but the pistons are raised. I'd like to use this block on my '76 2002 but I'm not sure if my head will work with those pistons. TIA