This page from the 1979 Denys Fisher (UK) Catalog shows an early sketch of what would later become Power Action Superman. It’s not known why the name was changed.
A few years back Benjamin Holcomb interviewed the late John McNett (director of preliminary design) he explained that the Power Action Superman was originally designed to made out of metal and that the idea was scrapped out of cost and safety concerns. He was shocked to discover the item had been produced!