LOL I run ito this problm some years ago
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It was the fuelpup lever that stopped the cam.
Remove the pump and it comes out.
In your case it also might be a lifter clearence problem.
If in good condition it is a peace of cake to remove the lifters. If they are stuck or rusted in you can soak them with wd40 or similar stuff and pry them out of the bare engine with a wooden stick (broom ore something).
Frank
