I finally went today to the other place where this ORG keeps the uniforms found on site. They scanned the whole terrain of the war zone with archeologists and metal detectors. Set a parameter and digged carefully and found not only the props and equipment from soldiers, but also their bodies and uniforms.
Shown here are some of the most known typical uniforms of the war. It's known that usually the colors chosen reflect the ones of each country's flag. Same thing here but the similitude I'm sure created some confusion that during the battle must have caused quite a stir and fatal errors in the craziness and adrenaline of the moment. Peruvian officers used the Prussian style of the era like this which I'm glad to have now at my disposal for the film. Here they are displayed on manequins so they can be appreciated at full:
Now, the peruvian soldiers mostly used creamy white uniforms with black shoes as you can see here (it is heavily dirty with soil and dried blood from the soldier):
Now this is the chilean soldier's uniform. Notice the similar colors with the peruvian officers (deep blue jacket and red pants). They didn't use high black boots though but khaki/brown colored ones.
The hats (kepis) will use the same shape of the Civil War soldiers; a flat foward-inclined top.
Now my next step is to do a walk-thru of the location I chose for the battle scenes: the Morro Solar by Chorrillos. Taking pics and studying maps to check the terrain and altitude beforehand.