I don’t know where stacks best position is because he can play both. Maybe richo is right because we do have options down back.I really like the promise Daniel showed down back in 2021. And I agree with Richo re the Stackman. If Sydney is on his game I’d certainly prefer him ahead of George.
Stack can replace Castagna because he can take a grab as well as play at ground level as George can ( or used to ) but the thing he may not have is the pressure that Castagna puts on defensively.