1. Remove all of the lifters and fuel pump. They can interfere with the cam lobes and journals.
2. Remove the distributor.
3. Remove the screws from the cam thrust plate behind the timing gear.
4. Make sure the crank is oriented to clear the cam.
If the cam isn't stuck solid in it's bearings, I can't think af any other thing that could be restricting. Hopefully it's just an oversight and you've already discovered it.