SBCs might actually work. Add the preempt_rt patches to the linux kernel, and that gives you the hard timers you need. With the preempt_RT patches, the interrupt reaction lag is < .25 milliseconds. Without the patches, you can still do a lot of traditional micro controller types of things as most things that use a microcontroller, can lag much more then that. To put it into perspective, 100x more then .25 milliseconds, is 25 milliseconds, or 25/1000ths of a second. So how accurate do you have to be.. 
Thus the reason why it is a debated topic, and really a gray area.
Woodgas is using natural aspiration, the electronics are greatly simplified over using EFI. The ignition is probably the hardest part. And I should note somewhere in here, because of the magnetic field interference of the engine, everything needs to be shielded.