Okay - so now it's time to go back to the necessary three - spark, compression, fuel.
1- check for continuous spark while cranking. Also verify that the I on the flywheel (under the little inspection cover) is visible at the same time piston is at top of stroke (proves that ignition timing should be correct)
2 - check for compression - use a compression tester.
3 - check for fuel - use starting fluid... does it try to run for a second or so? Then it's likely a carb issue - they're famous for getting dirty when sitting for a while.