Marcus,
After cranking the engine, check the spark plugs. Are they wet? Dont want to rule out the compression in the cylinders. Has the head been torqued down correctly? Or you might have excessive leakage.
Not sure on the electricals to the coil and distributor. Can do a search on ignition wires or electrical diagram.
Walter Klatt
1967 220SL-diesel
1963 230SL-gas