In my travels, one thing I've found is that it's the Mazda L block that forms the basis of the current 4 cylinder Ecoboost engines. Ford now put their own DiVCT direct injection head on them - likewise Mazda do the same with their SkyActive heads. But otherwise you could fit up a 2.3 Ecoboost into any previous Mazda-L or 4Cyl Duratec directly to the mounts and gearbox, as long as you were happy to build custom exhausts and inlet and had a good enough aftermarket
ECU to drive the cams, direct injectors and torque-controlled turbo.
So the Mustang Ecoboost and Focus ST/RS are running Mazda blocks still. Or at least if Ford are casting them, they are still cast to the Mazda design.
Luke