In the case of CKLW, they had been top 40 for several years, but it was "The Bakersfield Sound" "The home of the happy fellas". Very loose and unfocused. In April 1967, Paul Drew instituted a "fake Drake" format as "Fun Radio 8". Drake signed the national contract to program the RKO top 40 stations in July, CKLW became The Big 8 with the Johnny Mann jingles and the whole package in July 1967.First, WOR-FM in NYC was never like KHJ or KFRC or or WRKO or WHBQ or CKLW or even KAKC or KGB. It was a modified format for that market and it was not truly successful. All the others were (Except for trying to make a 250 watt station in Cincinatti work against WSAI).
RKO did not develop a format; they hired Bill Drake as consultant and Drake brought in Ron Jacobs for KHJ and Tom Rounds for KFRC. RKO did that because they were clueless on what to do with their stations. Drake had developed his format in Fresno competing wiith Jacobs, in fact.
For the actual KHJ story, see BOOKSHELF: Programming - Personalities - Techniques and look for "Inside Boss Radio" by Jacobs on the first line of listings.
Drake did not do a tighter Top 40. Drake and Jacobs developed a much faster and precise presentation with very short and aggressive jingles and avoidance of what Drake called "the Bakersfield sound" where jocks rambled and had poor pacing and excitement.
In fact, Drake and Jacobs in LA developed a format that had more precise use of gold, expanding the "just 40 songs" list to very strong older songs.
WOR-FM was interesting. It musically was the live version of the syndicated "Hit Parade" format. Same jingles (except "The Big Town Sound" replaced jock jingles, 20-20 news (straight but upbeat newscasts) and eventually morphed to top 40.
WOR was so successful that Drake was never going to get the AM, though a head-to-head Drake/Sklar battle would have been epic.