Well, we know why the camshaft is bad....
The housing that acts as it bearing and provides the lubrication passage to the bearing surface is mounted up-side down....So NO oil to the bearing or camshaft end...
There is no current need to remove the valve springs and valves....You would need to remove the tappets to do so, and that requires removal of the two head covers/cam bearing castings anyway.....
To remove the left-side head cover (that is what Honda calls the casting that acts as a bearing and houses the advance mechanism and point plate), once you have removed the four screws and the advance base, rotate the camshaft until neither left valve has any pressure from the cam=lobes and tappets.... The casting SHOULD simply pull off, but considering it is likely extremely galled you may consider using a hardwood dowel as a drift to drive it out.... It MAY facilitate the process to remove the tach-drive side by making a similar adjustment to free the right side valves, and pulling it off first.....
Feel free to phone while doing this...... 540-525-5199....Steve