I think breed clubs don't set the APA OR ABA standard they just adhere to them..
I think if a project bird makes it, it will be up to the folks showing them to get them in the books and not up to a certain breed club, but rather through the ABA or APA, of course using the books of standards is something to use as a tool to get the project birds within similar leg color for that particular breed or suggested leg colors, comb types, egg color, lobe color etc.
Remember different breeds of chickens will and can be used in projects at one point or another to maybe gain certain abilities for the project birds. One may consider using an excellent egg laying type to add to the mixture or using a certain breed with better disease resistance, or even breeding for more broodiness of the project birds or what have you. But the end focus will be on body conformation and plumage colors..lots of work, but lots of fun as well.
Charlie