You should have gone to a library and gotten a book on small engine 4 stroke repair, one with an overhead cam section might have saved you this problem...
The part you missed was that BOTH the crank and cam have to have their locater marks lined up correctly.
There is either an inspection cover on the flywheel... or you have to remove the side case to find the marks on it.
You ain't the first one.... by a long shot.
A whole lot of American hillbillies have had there asses saved a million times because American V8s with pushrods don't have overhead cams that have to be timed after only the heads have been off.