I am doing similar within American Games. The barring allele is sex-linked, but that will make no difference with respect direction of cross you and I are making. All chicks will get a single copy of the barring allele from dad and a copy of extended black from mom (dad carries extended black as well). Therefore the chicks will be black with barring. Unlike with the Barred Rock where you can discern sex by intensity and size of the whitish patch on head as impacted by whether the chicks have one copy (female) or two copies (male) for barring, all your crossed chicks will have one copy regardless of sex. Upon maturity the pattern should be less sharp compared to even a Barred Rock hen because you have another gene or two that tightens barring pattern that is diluted. The final product with respect to coloration will be intermediate between a Barred Rock and American Dominique hen with a dumpier build coming from the Brahma side.
My birds will not be dumpy nor as large.