How easy/hard is it to replace a right hand engine mount and the distributor O ring?

How easy/hard is it to replace a right hand engine mount and the distributor O ring?

Driver's side mount is held on with 1 through bolt to the body work and 2 nuts and one bolt to the lower engine mount. All 17 mm, IIRC, you may need a deep socket to reach some of the nuts.
Use a piece of wood and jack under the sump to take the weight off the mount when you pull the centre bolt out.
The central bolt can be a problem with seizing. Work the bolt back and forth while running some lube down the bolt if it is tight on the way out. Take your time as you don't want to strip the bolt hole in the lower alloy mount.

No idea about the "O" ring though.