I used the Cardone 13-2881 master cylinder and this adaptor Brass Adapter, Female(9/16-18 Inverted), Male(1/2-20 Inverted). Everything just bolts up. I did some other brake upgrades at the same time but my pedal feel is much better and I am happy with the upgrade.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1