I think that these designs might fit the QK75 really well:
YMDK Rouge Gradients OEM Keycaps
Epomakers "Botanic Garden" Keycaps Set as well as their "Barometer" or "Enlightment" Set
Is there any specific color theme you want to go for? Cause I think that those lush/pastelle Keycaps from Epomaker really fit the Milky white color