IMO: I would think the white rocks would be bred to the barred's for size, but I don't see how that could tighten up the bars. Never did it, so I don't know. If you have decent birds to begin with, you should not have much trouble with the barring as long as you pay attention and find out how to do it. I would take those light males that you are going to get and if they had the type mate them with the darkest female I had with good type. Hopefully a very dark one. Some of you know that there were two varieties of barred rocks in the old days. Light and dark were in the SOP, so you will get these variations. Think about it before you cull them.
My first barred came directly from Ralph Sturgeon and even I could not fowl them up. In 1979 Ralph judged the rocks out here at the APA National in Pomona,CA and gave me one of the greatest moments in my chicken life. A RB in a huge class of LF rocks. I have had some great wins in my life, but placing that high with a huge class of Rocks was the high point for me. Oliver Bowen had BB with a white.........the best part for me though was Ralph Sturgeon judged the birds. He was the only living expert on barreds at that time.
They are a gorgeous bird when correct. I will have them again.
Walt