Principled BSDF specular

i’m new to blender and i have many material in the specular-glossy format.
I noticed the principled BSDF in blender don’t permit to input directly the specular texture to the specular channel, because of different interpretation of the “specular value”.
I don’t know if exist a simplified method, but i have prepared a conversion method valid for every specular value.
It’s based on the formula in the help system: specular=((ior−1)/(ior+1))2/0.08.
Obviously, the imput texture is expressed in 1/IOR value derived from the LUT downloaded in corona forum (many thank’s to great user dubcat).
The lut must be applied in photoshop in 16 bit mode to the specular channel, then loaded in blender in linear gamma (non color data).
When i understand how to do it, i will attach the files with an free asset example.

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Ah… Sorry for my english!!!