Non return valve in sump extension.

[Rasputin]

Im thinking about fitting a NRV in the hole in the sump extension. A simple ball valve with adequate flow to allow scavenging from the sump but closes when the engine isn’t running to stop the oil in the scavenge pump and lines returning into the sump.
Any thoughts. 

[scrambler]

What`s wrong with check valve in the engine case? Did you try to fix that?