You really should be getting a spark, i had a problem with mine not starting a while ago due to being frozen and i remember laying the plug/coil onto the top motor mount i think to check spark, and would get a consistent spark. So if you put yours there, it should spark. Do you have a DVOM meter? try checking the resistance between the head and negative cable of the battery. Double checking nothing bad happened when the flywheel was removed/installed was a good idea too
Your cam timing (some people call it valve timing) still seems the most likely culprit. Its not as straightforward as it should, lining up the marks, especially with the cam mod done too. Easily could be off. You referring to a manual for how to do it?
I think a compression test might be in order too, quick enough to do
I have seen a lot of the intake boots tear too, usually tears inside the boot where it wraps around the carb, could have happened when you put the carb on or took it off