For barreling a Lee Speed "replica" or rebarreling an original, the Lithgow SMLE heavy barrels in .303 are still available sometimes in Australia. They were made in two versions, the earlier one having deeper cut rifling. I wish I had imported a few more before Australian export regulations became so restrictive. A few have shown up fitted to Lee Speeds on this forum and others. They are easy to ID by the shoulder just behind the front sight where the barrel is stepped down to original SMLE dimensions to allow the use of the same frontsights. There is also an "H" on the flat of the Nock's Form, but that would probably be removed on some polished and blued barrels.