Thanks for the info. A little too pricey for me since my car is not 100% original, it's #'s matching engine/trans but more of a minor resto-mod and dont care to keep it totally original down to little things like a master cylinder that isnt T/A or vehicle specific. But thats great to do for all original cars.
The china acdelcos or other brands may be cosmetically a little different but functionally they are the same, and for many brands the quality is pretty good when made overseas compared to no name or cheaper rebuilt parts store stuff. For many items china is capable of producing excellent parts when held to a high standard by the company contracting them, its the super cheap brands that dont care much about quality control and only in it for money. Also the AC delco masters are new, not rebuilt... I'd rather have a decent name brand new part than a no name rebuilt part like many parts stores parts are.
With that said, I have owned this car for 20+ years and the brakes always worked fine, re-did everything with new parts like calipers/wheel cylinders pads/shoes & hardware, but over the last 10 years or so the pedal wasnt as firm or responsive as i remember or compared to my other cars, with the new master the brakes feel like a new car. Guess time will tell how long it lasts but all the positive reviews this part gets, it should last a very long time.
Thanks again for the info, I may hold on to the original one and rebuilt it myself with a kit... thats probably made in china.