I wouldn't buy a timing light just yet. Most likely dealing with high resistance in the starting circuit, whether it be cables, connections or the starter itself. Sounds like you are on the right track.
The crane unit is indeed an externally mounted electronic ignition. I believe they use the stock rotor.
REBUILDING HOLLEY MARINE 4160 CARBURETORS - $199 DELIVERED
GENUINE MARINE HOLLEY KIT USED - INCLUDES POWER VALVE UPDATE
LED TRAILER LIGHTS, LUG NUTS SPARE TIRE CARRIERS, SAFETY CABLES....
Originally Posted by Bouyhead
Installed my carb that was rebuilt by thatsmrmastsercraft, Thanks Peter!! Hot or cold this boat starts and runs like it fuel injected.