You can remove the head without removing the cam; however, that leaves bolts stuck between the head and cam towers. You can't properly measure a bolt that's stuck in the head. So if you have to remove the cam at some point to measure the bolts, why not remove the cam while the head is attached to the block?

How does the A-B light help you set the engine to TDC? The RIV setting is closer to 14* ATDC. As a matter of terminology, RIV is an arbitrary value which has nothing to do with when the inector fires. The injector fires at about 24* BTDC. Chalk this up to the engineering prowess that brought us captive head bolts and soft connecting rods.

You can probably snake the head away from the fuel filter unit IF you remove the cam. Far too risky to slide the head in any direction with valves open.

Sixto
87 300D