Idle speed is a little high, try dropping the idle speed down to 700rpm and see if the carb adjusts better. You may find once the carb adjusts you won't need the higher RPM. If the carb adjusts at the lower RPM but when you drop in gear the idle is too low, we'll work on that next.

Sorry, I didn't explain. The drawing shows you a way of checking the balancer on the front of the motor for slippage, which was mentioned as a possible timing error problem. Check your balancer to make sure it has not slipped throwing the timing marks off. And please verify the timing marks line up once you find true TDC.

That plug looks good aside from the oil leaking on to it (probably valve cover gasket), also a picture of the face of the plug would tell us more. And would help to see all the plugs as they are the windows into the cylinders. I have spark plug racks that I use to keep the plugs in order to the cylinder they came out of. You can use a piece of cardboard with a hole for each insulator tip and marked per cylinder. It is a useful tool to keep track of your tuning.
plug rack.png

Your boots are definitely burned, watch it at night to see if it's arcing (even with new boots), this may be a big part of your troubles. As I said, I have to run ceramic boots on mine.