I have never used ox heart but my husband likes sheep hearts. I stuff them with sage and onion stuffing and roast them slowly. Best used cold. Daresay ox heart could be done the same way. Wrap it in foil to cook. Cooking it too quickly will toughen it because it is after a muscle and will constrict.
Lambs fry I soak in milk for half an hour before cooking. Clears the blood and sweetens the meat.
Tripe is horribly expensive these days if you can find it so haven't had that in a long while.
You can have the pigs heads.
Once upon a time there was no such thing as left overs from the carcase even the dogs were fed. That is until hydatids put a stop to that.
