How to change color for brush strokes in Photoshop, very specifically even if some have transparency

Hi,

I created an illustration using watercolor brushes so they have many gaps in the strokes to simulate real watercolor. In addition, some of the layers utilizing this effect have the opacity turned down for a transparent effect for blending effect.

I need to convert the same 3 colors I utilized for each brush stroke to different colors. (specific colors)

How can I achieve this considering the delicate nature of each watercolor brush stroke and varying opacity %s factored in?

I need a bullet-proof technique.

Thank you.