Try sky replacement

Skies are often completely blown out in old prints, so there’s no detail there to work with. If you want to add your own detail, why not try using the Sky Replacement tool? Go to Edit > Sky Replacement, then choose a sky to add to the scene. Choose a sky that suits the scene, either by using the list of default skies or by loading in your own photos. Fine-tune the colours to match land with sky, then add a tonal effect on top to bring everything together.