If I remember correctly....and I may not be...the Shackleton was based on a Lancaster airframe? What about "adapting" a Lanc....if you can find one of those!

Gow589....looks like a Herc?

Spad... you're right...many turboprops feather when they shut down....but some stop in flat pitch as well... the Hercules and Orion both do(mind you they use the same engine...)