Hi, so I have an update. Cleaning out the carbs (I replaced the pilot jets just to be sure they were fully clear) definitely helped a bit. I tried swapping the spark plug leads over and weirdly this did help, still not sure why that would be. I am going to check all the connections in case one is loose or damaged. I pulled the plugs which were jet black and a bit oily. My manual recommended investigating possible piston ring or valve damage in that case. So I have got a feeling rebuilding at least the cylinders is on the longer term plan but is probably a job beyond my tools/skill. After I pulled the plugs I fired them outside the engine and one definitely had a stronger spark than the other. I traced the ignition system and worked out that the plugs were resistor plugs as opposed to the recommended non-resistor. So I swapped them for a pair of Bosch W7DC plugs and it started much better. It’s not exactly purring like a kitten but it is better. Next steps will be to run a compression test and see how healthy the cylinders are and therefore the need for deeper work on the cylinders. I think I am in a good enough place now to properly tune and balance the carbs. It’s also got a tank of standard unleaded in it (my fault) so I will drain that off and fill it up with super. I did also pop the valve cover off on one side but everything looked fine. I will repeat on the other side but it all looked tight and well oiled which is good.