Not to stray to far from the OP's topic but I feel we have raised some very good points when using WMO etc. You can never be to safe and I like the magnet idea to catch stray metal particles.
Josh what type of magnet did you use. I know Neodymium are strong and aren't to badly priced on Amazon yet they are mostly smaller magnets. I am thinking about getting some and running the used oil over them to collect any possible metal shavings.
On a side note I do like the idea of the mechanical shutdown. Could be used for safety and I wonder if you could incorporate a fast idle with it. It would help warm these engines up during the cold days.