When I am dead, "they" can do whatever they like with my body, it'll just be meat, I'll be gone and not needing it any more. No different to a side of beef, a pork chop or a chicken breast. Once we have died and departed there is no longer any difference. Whatever name you give it, your mind, your soul, your spirit, this is what makes you you, and when you die this isn't present in your meat suit any more.
Anything that can be used to save or improve lives, they're welcome to. The rest, burn it, preserve it as a specimen, whatever. Hugely preferable to the robbing *&^%$'s who run the funeral services ripping off my offspring just to dispose of my vacated meat suit.
It's the living who matter, not the dead.