Some few days past, Tim Daley posted about fatal rollover accident and importance following safety rules.
Tim's post inspired me to begin layout of DIY ROP for Ford 8N tractor, which hopefully I'll begin welding up tomorrow.
In the meantime, another potential safety device came to mind: An old school liquid mercury contact switch, as used in mechanical thermostats, could be placed in series with 12 volts going to distributor coil.
Mercury contacts would be adjusted at such an angle, switch would normally pass 12v power to distributor. In case of rolling over, however, tractor's angle would pass "set point" and mercury would slide back away from contacts, cutting power to distributor & shutting engine off (see url photo).