What's the issue you are trying to solve? The newer aluminum master cylinders + the AR Engineering adapter should take the stock length pushrod. This is with manual brakes.
My guess is that adapter isn't as thick as the one I linked to. That would push the brake pedal back and make it high. An adjustable pushrod would fix the issue.
You could also add an aluminum shim behind the existing adapter. You could experiment with washers to get the thickness correct. Which ever is most cost effective.(a shim, an adjustable pushrod or a different adapter)