Listen to Southern, she knows dogs. And please don't think it was your post that caused a disagreement; your post was only asking for help that probably many others need too.
If you have 20 acres could you maybe find an older experienced LGD that could come to your place to live? It sounds like you have enough land for 2 dogs. I have 2 on a lot less land and I like having 2 dogs. My female is about 3 and my male is only a year. They work well together, they keep each other entertained during "down times" and they do an awesome job patrolling together at night, they are truly amazing.
My male is still a pup in a lot of ways, but I have no doubt that he has learned much of what he knows from my female and from his parents; he was 6 months old when I got him. He does have a chicken fetish, but he is awesome with the goats and I know he will outgrow the chicken thing. When I first got him he had been around cattle, no goats. He wanted to play with my goats, he would run towards them when they got active and it had me a little worried at first. Until my female intervened; she would just simply sit between him and her goats. It was pretty amusing to watch. Kids are just around the corner so I will be watching him closely again, but I know my girl has it all under control.
I hope you find a solution, I know how hard it is to get rid of animals that we like, even if it is for a valid reason.
And about the cat killing...cats can't get into my pasture unless they go over the fence, but chickens or guineas that come in and aren't the usual part of the pasture flock had better fly out in a hurry. My girl won't allow any strange birds in her field, even if she sees them every day on the outside of the fence they are not accepted on the inside. I am sure it would be the same with a cat.
I'm clueless on training dogs, but there are some who do know a thing or two . I would find someone like Southern who is a trainer in your dogs breed. And stick with a program. IMO. Its not late.
