The OP's bicycle is a 1987 model manufactured in, I presume, late 1986. I've seen this scheme before. The mixture of Sante derailleurs and shifters combined with New 600EX crankset, brakes and hubs is the OEM configuration. Original retail price was $750 US. Please post the serial number for my database.

Norco, to the best of my knowledge, never manufactured any frames. All the Canadian Nishiki, were designed/spec'd by Shields and later Norco, but the frames used the same sources as the USA models, typically Kawamura or Giant. Canadian models could be virtually identical or drastically different from their USA cousins.

The frame does not look too bad from the pics. I'd spot remove and neutralize the rust using oxalic acid or simlilar solutions, then touch-up.