best way to do it is as described above,check for cracked sleeves for sure, you want to make sure you have both the head and block done before you put the headgasket on to make sure you have a level surface. alot of people just get the head done and then install everything back together and never have a problem, but theres always a chance the block somehow warped as well. pulling the block will definitely help in identifying any cracks in the sleeves cause they can be tiny little hairline cracks that you might not be able to see if you dont pull the internals out and look at the block up close and out of the car.