Got fuel, spark, comp but no start

Sounds like a problem with the fuel supply to the carburetor.

If there is a lack of fuel supply it will take a lot of cranking before it will run, it will eventually fill the bowls. fire up and run...then run dry and stop.

Replace fuel filter with a new see-through one, Rig up a fuel line from the inlet of the fuel pump to a jerry can filled with fresh juice.

If nothing else it will eliminate one more potential cause.