If the exhaust leak is between the head and manifold there may be a vacuum leak there too. I don't see how it could be so big as to not let fuel get to any cylinders. Check that by spraying starting fluid between head and intake ports while someone cranks the engine. Be careful of back fires! I'm not absolutely sure of this but I think there are two types of aluminum cam gears. One is all aluminum and one has a steel core. I have heard of the gear shifting on the core thus changing cam timing. First I would check ignition timing and ALL wires, coil condenser etc. If no go I'd squirt fuel directly into the cylinders. If no go I'd pull the valve cover and check rocker position relative to #1 piston. Pretty much as you would when adjusting valve lash. Good luck, let us know what you find.
