Saw one slightly larger that actually ran on GAS . The blue prints are the hardest part . a GOOD machinist can do that . The guys I worked with back in the day would have no problem with it . They worked in .0001
so did I. On an EDM machine. I could put a .005 hole through a 1/4 carbide ball.
http://www.youtube.com/watch?v=jg0k7zDsB8w
Now that may be bigger but harder to do ( ignition distributor and carb had to be made down sized)