I've been following this project, (well as much as the bugs allow) and I'm impressed, this is a very good way to utilize excess wood to convert it to usable power!
Once you get done, I'd love to see the sizing on your components, engine, etc,and alternator.
The only thing that does worry me about this project is the longevity of a small single cylinder engine. Most rely on the gasoline itself to help in lubrication. However if you're constructing it out of hand-me-down components, I suppose that isn't a big concern.
I also think I missed what it is you're using for a cooler.
I could also see a larger setup using a 4 cylinder engine, and a much larger alternator onboard.