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.
Two Chrome 10 hole wheels with Kenda Loadstar radials.
Mounted, balanced and delivered.
PM or email me for tire, wheel or package pricing.
CARBURETOR REBUILDING - $199 Parts, labor & return shipping included
Holley Marine 4160 Freshly Rebuilt $349 - Delivered (no core charge)
2 LED 6" BRAKE LIGHTS DELIVERED $32