Just a random bit of info on Heelers and poultry... Many breeders exclusively breed for sheep/cattle/similar herders, and at no point allow their dogs to access any other livestock, precisely because they do kill them.
Trust me I hear you... Out of my three Heelers the eldest one I'm honestly not worried about, he is the most gentle dog there and mostly ignores the livestock and any wild animals and does his own thing, he loves herding though, he will spend all day playing soccer/herding a horse ball around the pasture... His cousin that is 2 years younger is the wild one, I don't trust her at all you can see the hunt in her and she is the one that has killed anything that gets inside her fenced area... And our youngest is hit and miss, he is just over a year old and he seems to copy whatever the dog closest to him is doing and hasn't really shown his own personally all that much...
Right now all three are sharing part of the chicken coop as their 'dog house' so they are in full view of the chickens all day, but separated by two fence walls my hope it that they learn the chickens are my pets and part of the family by seeing me interact with them everyday... I hope that provides at least a solid base to work on further training... I did the same all summer, the pasture the dogs were in was adjacent to the pasture the goats and llamas were in, so there were in view of each other all day and the dogs got to seem my interaction with the goats/llamas letting them know they are part of the family... If nothing else the llamas now pretty much can identify and ignore my dogs and accept their proximity, even though I hear that llamas don't really have much ability to distinguish K9 friend from foe in general ...