Without a doubt those two combinations laminated together will not only be strong enough but look very well together. I am currently working on a one piece recurve with that combination, plus with a thin line of maple for an added touch. I am confident of pulling 45 to 55 pounds without any issue.
I realize that both black cherry and black walnut are or not in the top of the hard woods for strength but the bow I am currently using draws 44# of a mainly wild cherry riser with one lam of ash through it. No problems with strength. Don't forget that the glue lines make the riser stronger, as well.