LA small block timing is suddenly way off

... I cannot rotate the distributor any farther advanced because the distributor cap mounting ear contacts the riser of the intake manifold. I think something may have slipped a cog?.. Sorry I don't know if the LA camshaft is driven by a chain or a gear. Is it possible my camshaft (chain) has slipped a cog? Or is there a way to remove some screws to advance the distributor rotor by about 30 degrees so I have some room to then adjust timing properly by rotating the distributor? I am stuck.

Not sure about your other problems but you can always move all the plug wires either CW or CCW one position on the distributor cap. Then No. 1 will be in a new position, and you can start over.