I have a Pioneer med radio just like that. It was one of the first Maryland State EMS radios used beginning in 1973 or '74. So yes, it's appropriate for a '75.
Indeed, I keep mine in my '70 Volunteer, which became the first (so I've been told) paramedic unit in Western Maryland in '74 and certainly had a Pioneer State radio in it.
I think APCORs were a little later, don't know when they came out. My ham radio friends tell me they are usable for ham purposes, which is why they command a higher price.
(By the way, I acquired my Pioneer med radio several years ago, and it proves it's nice to have friends in the right places who know your interest. A friend of mine was teaching at the county fire training center. They were cleaning out an old supply closet, and he saw this "old junk radio" ready to be thrown in the dumpster. He knew what it was, and grabbed it for me. And I've been eternally greatful. As far as anyone can tell, I have the only surviving Pioneer Maryland State EMS radio.)