[utopia]

Any supplier of threaded fasteners should be able to supply the right handed bolt but the left hander might be more tricky.
Either way, you'll need to specify the thread diameter and also its pitch.
Most metric threads are a std pitch though (usually from the "coarse" series but there is also a "fine" series and a few "specials"). I suspect you'll need the std (coarse) pitch.
I get mine from "All Screwed Up", Leicester.

Another way might be to just use some washers to take up the excess thread on the std bolts.
Or for a slightly neater job, get some spacers made up instead of using washers.
Black nylon ones would look neat and not rust.

ps. this was written without having actually studied the particular arrangement on the 1200s.
I assume its the normal set-up but a pic would clarify.