Hello out there! 
That’s an interesting mix you’re considering! A Silkie Moorhead Silver Partridge rooster bred to a Silkie Buff hen wouldn’t typically produce a black-headed white Silkie. The Silkie breed has some complex genetics, and the head color tends to follow the overall genetic makeup of the bird..... With the Moorhead Silver Partridge genetics, you’re more likely to get offspring with partridge or a similar coloration, but not a solid black head. 
The white Silkie head generally comes from other gene combinations, so it’s a bit of a genetic toss-up. If you're aiming for a specific look like a black-headed white Silkie, it may take a few generations of selective breeding. But hey, you might get some beautiful surprises in the process!