the only way to tell for sure would be to breed him but if you breed him to the black tailed whites you might get all black tailed whites or a 50/50 of whites carrying the gene for black tails and black tailed whites or maybe all whites carrying the black tailed gene. im not good with genetics though. i do know there is a chicken calculater you could use also but if he has different color genes in hisbackground chicks could come out with more color. again there is no way to tell unless you breed him.
oh yea the hens may have other color genes as well, or you can keep searching for white hens or get some eggs shipped to you and hatch them (by all means if he came from a good breeder stay away from hatchery