Technical where to buy / what brand of 40' style master cylinder is worth a darn

Im tracking down some brake problems in my Av8 and I'm thinking I have a faulty master cylinder. I have 46 lockheed brakes and 39-41 passenger car pedal set. masters appear to be all the same from 40-52?

The last master i bought from RockAuto, and maybe I just lucked out because its been fine for 3 years without issue. It was for my 50 F1. Im worried about offshore quality for my roadster.

 

if you have a Napa nearby, you might want to try them. the last one I bought they had it in stock. And that was only about a year and half ago.