Jack Cook wrote:
I the last scene were Briggs walks up all beat to heck just before he gets into
the car you get a quick shot of the stern and it say.....ANZIO ie USS Anzio CVE-57

Navsource.org has the Anzio being stricken, sold and scapped in 1959, some 13 years before Magnum Force was filmed. Most of the Casablanca-class escorts were scrapped by the early 1960s, while the Commencement Bay-class, which the Rabaul and Badoeng Strait were part of, lasted until the early 1970s before they, too, fell too the cutters torch. Surprisingly, some of the older Bogue-class escort carriers found a new lease on life opearating as aircraft ferries through the Vietnam war. Apparently, they were more efficient to operate than the newer classes of escort carriers.
I'm inclined to agree with the IMDB poster on the identity of the carriers. Both carriers were sold for scrap in late 1971 - early 1972, putting them right about the time the movie was filmed.
It's a shame that no examples of an escort or light carrier exist. The NHC should be ashamed of themselves for letting the Cabot slip through everyone's fingers.