The Colnago website states that the Precisa (straight blade) fork was created in 1987. It was not available as an option to the consumer until 1989. (The 1988 catalogue does not have one image of a straight steel fork).
Even when the Precisa fork was available as an option, it was initially slightly more expensive, and many buyers chose to get a conventional fork rather than a Precisa. I recall listening to Paul Sherwin in the early 90s when these forks started appearing on several team bikes in the TDF. He was speculating that the high number of crashes was possibly down to the straght forks making the bikes less stable. Not surprisingly, it takes time for cyclists to change their ways, and this sort of thing doesn't help...
Old habits die hard with cyclists, as many on this website will attest. We prefer the nostalgia of a traditional bike over the newfangled gimmicks. The Master is still made today with the option of a curved fork, despite the availability of lighter stiffer materials.
Assuming that the parts on the bike are the same parts originally used to build up the bike, one only has to look at what I wrote in the paragraph above to answer the question of why the original owner chose to build his bike up with Nuovo Record instead of C-Record. C-Record was developed in 1983, but Super Record was still produced by the Campag factory until 1987, and continued to be sold for a few more years in shops until supplies dried up.