I don't think there is a reference anywhere. I seem to recall reading somewhere that most size and stature traits are a combination of several different genes. For instance, topline may be influenced by back length, hip width, underbody muscles, tail feather length, etc. Determining the outcome of all of those genes against the absence of all of those genes would be a mind numbing task.
Best bet, breed the best overall bird to the best overall bird and cull heavily (as Big Medicine reminds me often!). Most of the time there isn't an easy fix for what seems like a small problem, it involves years of breeding the best to the best.
There is a saying among old breeders, " You will get what you will tolerate " , Which I take to mean if you use a bird with a less than stellar feature in your breeding pen, don't be surprised if a lot of your chicks have it too.
Thank you both.