Did I Really screw up my timing

[NickCox]

Yesterday I put the Cylinder head back. I got it tightened on and every thing looks good. Except for my timing. The whole time the head was off the timing chain sprocket was held up by a rope to the ceiling. I never moved the camshaft or the engine while working on it. (That I know of.) Now the sprocket will not go on the camshaft. The one little notch is approximately a half inch away from fitting.

Is there a way to move the engine or the camshaft to line them up, without affecting the timing? Or do I need to do something else.

Any suggestions would be a big help. I hope I didn't mess this up to bad.