Correct value for a displacement map to match high res sculpt?

I’ve sculpted something in zbrush, baked a map from the high res mesh, exported the low res mesh and now I want to put the displacement map onto my model and subdivide the model in blender. The head on the left is the displaced model and the model on the right is a decimated version of the same model. I don’t know if the values are correct, is there any official value for these slides to match the original high res mesh? I’m not sure if I’m losing detail or if I’m displacing the surface of the model too much.

I plan to texture the model in 3d coat, if I get this displacment map to work correctly in blender. Would I export the low res mesh and paint on top of it or would I export the high res subdivided mesh with it’s subdivided UVs and paint on it? But most importantely of all, is there anyway to ensure the model gets displaced accurately?