A couple of years ago I did a post on the re-engineering of the Model A Engine by Terry Burtz, you can find the article here
Since that time things have moved on massively and Terry is in full production and selling not only the engine to the public but also many other ancillaries to match.
These include flywheels, cylinder heads and camshafts with probably more to follow
Also on the very comprehensive site are all the technical data and ordering information for this excellent piece of engineering.
The site is here