Rebuilding master cylinder - manual brakes

[spddm0n]

I just picked of my first C10 and the brakes need to be rebuilt (wheel cylinders all the way around and master cylinder). Since this truck is completely original and unadulterated, I thought I'd just rebuild the wheel cylinders and master cylinder, rather than put in some Chinese-made crap that you can buy in auto parts stores (all the Japanese cars I work on I have to source OEM supplier parts because all the American parts makers are making there crap in China and I just can't stand buying that crap).

I was surprised when I picked up the rebuild kit that there is only the primary piston assembly is provided. It does not include a secondary piston assembly. Why would they not provide all the parts? Would it be best to by a re-manufactured master cylinder instead? I didn't want a "new" one that isn't an original GM part if I didn't have to.

Has anyone else rebuilt one recently? Was the secondary piston assembly in good shape? I'm pretty sure this is the original master cylinder. It appears there really wasn't a lot that needed to be replaced in this truck's short 45K miles on the road (farm).

Also, if you have rebuilt one before, do I need to remove the little brass fitting in the hydraulic line ports? There are new ones in the kit, but I'm not sure I have a flared tube fitting (?) tool to install them.

Thanks for any advice you can offer!