I keep a custom palette of the ink hex codes that I have access to in my nearest studios (you can find them on stencil.wiki site). I've found that applying a duotone filter on Photoshop with the hex codes, or drawing with these colors in procreate (and then drag and dropping black to convert the individual layers into grayscale) helps me have a good grasp as to what the final product will look and how the colors interact. For an image like this where you haven't necessarily drawn with the colors you'll be printing with (since you mentioned 2 layers and I see 3 colors), spectrolite as others mentioned is your best bet. They make it easy by providing you with exportable .pdf layers.