Since you have spark, and I presume compression (does it sound normal when cranking?), it seems like severe flooding could be the issue.
But make sure timing marks are lined up when the small hole in the cam sprocket aligns with the hole in the cover behind it.
You might also try disconnecting fuel line from carb. Plumb separate flexible line from disconnected line to gas container, clear of belts and fan.
Now inject starting fluid or other suitable flammable liquid in carb air intake. Should be able to start and run for a few seconds, maybe longer depending on gas in float bowl.
Assuming problem was fuel, this would help you verify it.
Good luck,
Bill