The old site search from Google needs to be updated. Use the Search at the Upper Right, or use What's New in the center - it has a drop down arrow. You will need to change your Favorits by right click mouse and clicking favorites. Many of the posts in How to Use This Web Site are old so the links may or may not work. I have one hell of a lot of work to do!
The easiest way is to get another set of clockwise breaker points. I have heard of people using their existing breaker point assembly and re-timing it to the armature, but I've never tried it and it would mean that the contact arm is leading and under pressure as it rotates.
Also, does your magneto have no advance/retard? and if so, what's it off?
I see a lot of ML CK1 maggys on vintage Lister stationary engines such as my 1920s "L" and they have no impulse or advance retard. (well mine doesn't), also used on some pommy bikes of the era with the advance mechanism.
Don't see why you shouldn't be able to change the direction, like Craig says move the points base plate around so the points crack open while the armature is producing maximum voltage in your chosen direction and it should work (may need to lengthen a wire ?). Would be nicer with a base plate and points made for that direction but it should work. (don't have mine here at the moment to check but from memory there is nothing unusual in them)
Just remember what I heard a long time ago from a retired auto electrician about magnetos running on "witchcraft" !!
Try contacting magneto repairers to see if they have a wreck for the vorrect rotation you need. Worth asking at least. Use Dr Google to search for them or look up the maggyman in S.A. He and his wife are very helpful and reliable. I used him to source a rare size coil for a British Seagull once and to my surprise one was sitting on the shelf ready to send.