Complex sentence: McLendon is widely credited for perfecting, with great commercial success, the Top 40 radio format during the 1950s and 1960s which was first invented by Todd Storz and for developing the offshore pirate radio broadcasting to both Scandinavia and the British Isles.
Split into simpler sentences: McLendon is widely credited for perfecting, during the 1950s and 1960s, the commercially successful Top 40 radio formatinvented by Todd Storz. He also developed offshore pirate radio broadcasting to both Scandinavia and the British Isles.