Although my cuckoos didn't come from my own breeding, mine look about like yours do Steve - I highly doubt the skin/comb/wattles will ever get dark enough tho. The barring gene just interferes too much. In fact, my rooster's name is "Razzberry", because that's what appears to be sitting on top of his nose where a mulberry comb should be...
I'm wondering tho, do you find that your cuckoos turn brownish in the sun? Mine look almost like DUN cuckoos, and then when they molt, their new feathers are black barred, making them look really splotchy, until all the old feathers are gone. Then the whole process starts all over again.