From the O.P.
In fact the entire tree of life can be reconstructed by comparing the amino acid sequences of this one protein. And yet any of these proteins can be switched and will work perfectly well.
Trees not only have ends, but also have trunks and branches. Trunks and branches are sequentially intermediate portions of trees.
Cytochrome C does not form a “tree.” None of the extant Cytochrome sequences are sequentially ancestral to any others (they can’t be placed into trunk and branches).
All of the trunk and branches that evolutionists propose for Cytochrome C are hypothetical, based on the assumption of common ancestry.