Nice looking bike! I think I can give you an idea of original components since I just acquired an all original 1950's Cinelli Model B. I don't have the bike in front of me, but here is what I remember:

Bars: Steel Giro D'Italia
Stem: Cinelli Milano steel
BB and Crank: Magistroni cottered
Pedals: Sheffield
Seatpost: Nitor 26.2
Saddle: Plastic with Unica on one side and Nitor on the other
Headset: Cinelli Milano old style
Rims: Fiamme red label (old logo)
Spokes: Stella
Hubs: Campagnolo "no record" high flange
Brakes: Universal Extra Mod. 51
Levers: Universal

Hope this is helpful.