I had written a post a while back about the Yomiuri Giants training in Vero Beach, Florida in March of 1975 and how a number of cards from the 1974/75 Calbee set featured photos from this. I've discovered recently that Calbee was not the only card manufacturer to use pictures from Florida - NST did as well.
NST's first card/stamp set was released in 1975 and was entitled "Mr Baseball". It was dedicated to Shigeo Nagashima, who had retired at the end of the 1974 season. There's a subset of the set that features photos taken during the 1975 spring training although it is not entirely clear to me how large a subset. Engel's checklist for the set lists a "Nagashima Training Scenes" subset from cards 174 to 191 - this subset includes cards of Nagashima with Stan Wasniak (then manager of the Dodgers AAA team in Albuquerque at the time), Gene Mauch (then manager of the Montreal Expos) and possible Jack McKeon (then manager of the Kansas City Royals). However there are other cards from the set that were also taken during spring training, like this one showing Tsuneo Horiuchi pitching to Ron Cey of the Dodgers:
This is card #224 from the set which is (clearly) not in the previously mentioned subset so I don't know how many other cards are from spring training. There do not appear to be any other cards in the set featuring MLB personnel that could have been from 1975 - there's a couple of cards showing Nagashima with members of the Orioles during their 1971 tour of Japan - two with Brooks Robinson and one with Boog Powell.