I really don't want to be on bad footing with you because you are a good spriter... but there is a flaw in what you are saying.
1. The original. Her overall body is 79 pixels, as you said. But her body only takes up 67 if the actual pixels, as shown by the magenta. The cyan is extra hang off like ends of pads and cape.
2. Jaw is brought in. Her body is 76 but 64 is being used. Her face is too slim, so let's bring the chin up.
3. Chin up. Her body is 74, 62 of it being used. Because her head is short and round and her body is smaller, she is now a lolita girl and looks like she is 14.
4. Igrune. Her body is 88 overall, but her actual body would be 73 on the sprite. This either means she is a man, or her armor is huge. But her armor is normal. The cape makes the illusion of making her look big. She is proportional.
5. Isadora. 66 body, 72 overall. She is pretty much the "average" that you said. But she is at a different angle than Eliwood. If at all anything, she should be shorter than the average you are suggesting me to make Eliwoman because of the foreshortening. She isn't 66 pixel round ball, so if she were at the same angle as Eliwood, she would be longer.
6. Syrene. 75 size overall, 70 body. Just like Isadora, Syrene is supposed to be foreshortened. Thus, if put in the Eliwood angle she would be long as well. She was already bigger than the average woman, yet still proportional.
Please don't get upset and all mad because I'm not agreeing with your idea. I'm not trying to be a bad person and trying to be better than you. I'm not going to be because you sprite more than I have. Art is art, opinionated, but anatomy is anatomy.