When you try to re-fire it and it doesn’t start, is the plug wet? Make sure there are no cracks in the pulse line. You’ll need more than two hands for the next check. While cranking the engine over, choke the carb. If it doesn’t start, there should be some gas dripping out the carb. When the engine doesn’t fire, can you get a spark grounding the plug to a fin? Pull the side cover off and check for a broken coil wire and for excessive up and down movement of the crank. If you have someone that can loan you a working coil, try it.
When you turn the motor by hand, does it seem to have its normal compression? If not, pull the head.
And don’t ignore the work you’ve already done. The new plug could be bad and the carb may not be assembled correctly.

Good Luck

Thanks for the update. We had gone for years without ever having a problem with a coil until this year. At the exit of a high speed turn, the engine had a hesitation. Turned out to be the coil.
Glad you sorted out your problem.