I reckon its had a respray, as there's not much chrome showing. I'm not sure about it being a Master, as these tended to be top-range with chrome lugs, shaped tubes and more complex graphics. But I'm not sure cos yours looks earlier than my period of colnago ownership (the over-bracket gear guides went out of fashion late 70's/early 80's)
I'm with LGF on campag record/SuperR groupset. Bars/stem probably cinelli or 3TTT and saddle a turbo or concor.
You'll need a english/italian (same thread) threaded headset and an italian threaded bottom bracket. Contemporary gearing will be with a five or six speed block. Sevens probably came later.
have fun collecting, building & riding it