Organs - your dog needs liver that is non-negotiable - 5% of diet, plus 5% of other organs including kidneys, thymus, brains, lung [sits in both camps - some argue it is muscle meat, some say organ], trachea, pancreas, spleen.
Introduce liver first and don't worry about the other organs for now. Do it very, very slowly - like 5g at a time for a retriever, much less for a smaller dog - trust me too much in the beginning can cause very runny poops.......I learnt that the hard way......