Squib said :
"Level sensors would be very difficult in a helicopter MGB... It would be better to introduce an emergency lube system."
Point taken, but an MGB oil level sensor and an emergency lube system are not mutually exclusive.
Tedeco and others make electro-optical fluid sensors that would serve the purpose. While not a trivial task to effectively install these or similar sensors in a slightly-modified MGB, it would surely be possible to do this in a much shorter--and less costly--time frame than designing and deploying either an emergency lube system or a run-dry system.