Creating a shader bassed on the Standard(Specular setup)

Hey all,
I'm trying to create a PBR shader based off Standard(Specular setup) that uses Specular instead of _Metallic.
I want to be able to modify the specular so I can have a falloff on the reflection.

Is there somewhere I could find the source file for this standard shader? Or how can I modify the standard one to accept o.Specular.

I assume I need a different lighting model to #pragma surface surf Standard fullforwardshadows but have no idea where to find the one I need.

Regards,
Lucas

 

As usual I spend hours trying to find an answer and as soon as I post the question on here I find it.

If anyone is interested this is how I did it.

replaced all referenced to _Metallic with _Specular

changed #pragma surface surf Standard fullforwardshadows
to #pragma surface surf StandardSpecular fullforwardshadows

changed void surf (Input IN, inout SurfaceOutputStandard o)
to void surf (Input IN, inout SurfaceOutputStandardSpecular o)

removed o.Metallic = _Metallic;
added o.Specular = _Specular