Just did a quick test how my 10years old models would hold up if the texture maps would match the nowadays PBR standards. Luckily I have all the PSD with the baked in occlusions on separate layer. So actually it was pretty easy to make this asset PBR proof. Back than we had only one cheap shader therefore I had to bake occlusion but even metal surface information with a wide fresnel of HDRI intro the color map. Today I removed all those layers and just let the metalness map and roughness map do the job with a separated occlusion map in Toolbag