I have used 12/4 Walnut without any issues for Cabriole leg stock. I have had really good luck buying from either Groff and Groff lumber (Pa.) and Good Hope Hardwoods (Pa.) for both 12/4 Walnut and Cherry.
Sometimes you can get away with a glue up, legs are typically not a place I have found you can get away with a glue up, without messing up the lines of the leg.
I used to live much closer to Groff and Groff, Good Hope,Hearne Hardwoods or Irion Lumber. Haven't had any issue calling any of the names listed, telling what I am looking for and let them pick out the stock for me. Irion Lumber was even a too far drive from my old home .
Everyone has their preference, but I think rift sawn stock (growth rings running diagonally from corner to corner) makes the most visually pleasing cabriole legs
Bob, Robert is naming off the first tier suppliers for leg stock used in cabriole legs. Those guys understand the need for riftsawn stock (appearance) with no runout (strength) through the ankles.
I would add Dunlap in Chantilly, Virginia as another possible source. He’s known for Pennsylvania/Kentucky rifle stocks, musical instruments and probably a few other items he supplies wood for. He also understands cutting and choosing the right stock for appearance and strength. I have had no trouble getting 3”, 3 1/2” and some 4” billets from him. Mine were maple and cherry. He has had walnut, I just haven’t used it.
I can’t tell you about having him pull wood over the phone, because I have always chosen pieces in person. Same for Groff, Hearne, Good Hope and Talarico.