If you’re looking to add the long tail to the mix, I recommend crossing to Hmong. Most of them have longtail genetics that carry over well into other game crosses.
This is a Liege x Hmong chick. His Mom is the splash Liege hen and his Dad is a 12 lb black copper Hmong. The last photo is Dad standing next to a full sized Isbar rooster. It’ll be interesting to see how he turns out! 🙂