Polly Engineering do it. Could also be scratch built using back issues of the magazine which have the drawings. Price about page 8, engine page 25 of catalogue
As you will see there are only 3 castings, some laser cut parts and a bit of tube. with postage to your part of the world it may be easier to source or make a flywheel and the other two castings can be machined from solid, tube sourced locally and either hand cut the platework or draw it up and have cut locally.
There should be a post here somewhere of one being built.
Edited By JasonB on 13/06/2019 07:44:26