Appreciate your input. And thanks for showing us your shop.
Yes, it would be a challenge. As noted there are concerns (probable be more), but with Jan's notes and with his and others help we can do it.
Can you give us some insight as why it would be too difficult? Because so far I just don't see it.
I haven't build an IC engine yet, so to me this would be great start.
The MK3 is a one cylinder ... that should be easier than say a 4.
No valves ... that's nice.
Vapor carburetor ... okay that could be an issue. Or better yet a challenge. Easy to make but could be difficult to adjust ... still worth a try!
Gears ... haven't made any before but maybe someone on the team has, if not then I would learn.
Spark ... yes that would be really different. But it is well documented.
Think about it some more and join us, we could use your well earned experience. No pressure ....