Managed to get another blank cylinder turned as the other one, along with the cover, has gone on vacation and don't know when it will be back!
I used my pillar drill with a 38mm hole saw and cut a recess down to meet all the sides of the cover. Then I cut another 25mm hole within that so the ignition switch can feed into the starter chamber.
Its a real tight fit (good!) so I think I'll just silicone it in place. I have noticed that if the switch needs repairing/replacing, I would have to break it to get it out!Silicone sealant will yeild eventually.
here's a pikkie with it on the engine;
As you may notice I took off the head and barrel so I can clean them and paint the head that graphite metallic grey!. Not sure whether to paint the barrel in black or leave natural.....