okay if there was a checklist made of what steps to take on a head gasket changeout for 85 500 sel:

what parts hit the machine shop? what MUST be replaced with NO question? where would you start? what would you take off first? and do what with these parts so as not to be harmed further by elements or be forgotten in re assembly... I knew I should have taken auto shop, any pointers out there for me at all? thanks a million