Harry, I have great sympathy with you. I breed ixworths myself and, like all creatures, each one differs slightly.
The original Ixworth was a cross breed itself, so it carries charecteristics of all the breeds. some of mine are smaller than others, some have slightly different combs etc. If you want uniformity I suppose you have to consider gm, which as a whole is not for us smallholders to tinker with. We have to use selective breeding. what your customer is really saying is he wants big ixworths, to go with his big ego. I recently bought some beautiful pullets from someone who has decided to give up with birds for a while. they were from different prizewinning strains, but once in amongst mine you can't tell them apart unless you really scrutinise them. my boys look very much like yours but I doubt they were that weight at that age. I have some sassos which I am going to cross with the ixworths to create a bigger meatier bird, if it works. Angie is right, try and get mr big to show you what he means, he might even let you borrow some of his superstock for breeding. My breeding programme is very much new, so I have not got any youngsters up to adult stage yet, but by next year I hope to see the full results of which of my stock gives the best offspring. I will ley you know how it goes as you are welcomr to have some fertile eggs.