Question for converting my brakes to dual circuit

[shok]

This is for my 66 c10. Two questions about switching to dual circuit, but still non power and drums all around.

1) Are the fittings the same size throughout the whole system? Like if I go to the store with my old soft line and the hardline there fits it then its guaranteed it will fit the master cylinder? (plan to use the same MC Sharps used, Impala model I think.)
2) Can I just make life easier by buying some brake line kit that has everything to restore the brake lines on a later model dual circuit truck instead? I'm on a budget but its worth considering.

I have the tools to cut and flare the lines already if that factors in the answer.
Thanks!