You are in desperate need of something 12br in 6.5lb-6.75lb range with 1/4---3/4 choking and 28" barrel length. It is internationaly acknowledged that the English made and make best bored barrels. Don't take it the wrong way, but there isn't much to pick from the list you have provided. May I suggest something of Birmingham manufacture with Sir Joseph Whitworth Fluid Compressed steel barrels?