Do vampires need most of their organs?

I’ve been thinking about Vicissitude when writing members of a Primogen Council.

One idea for the eccentric Tzimisce Elder NPC I have is for him to optimize his body.

The thing is, his body needs space. So do the kidneys, intestines, liver, gallbladder, lungs, and other miscellaneous organs need to be there? Or is replacing them with things that can pass the blood around fine?

This is a question about magical mechanics by the way. Science doesn’t apply to everything in the World of Darkness because Science is human magic. I’m asking about vampiric rules.

I know that the heart, brain, and stomach are all sorta necessary.

So could a Tzimisce scoop out most of the stuff I mentioned, replace it with balls of mutilated Revenant Animals (like a mouse or something), and use those as impromptu blood batteries? He has a process for sustaining them that’s related to getting a human researcher to do some modifications, so all I need to know is if the organs are necessary. Also he doesn’t give a fuck about how he comes across, so if this is a faux pas for his clan he doesn’t mind.

If it comes with penalties to Heath Levels, that’s fine as well. This guy doesn’t get into fights and two of my players could genuinely solo him in hand to hand combat.

So does it work? What are the rules here?