An additional discussion: It seems
Godzilla Vs. Megalon was produced longer than we thought!
As we all know from past data,
Godzilla Vs. Megalon was originally supposed to be a solo vehicle for Jet Jaguar (which was designed after the winning design, "Red Arone," of a design contest for children), fighting Megalon, a rejected Godzilla foe. The title was something like "Jet Jaguar Vs. Insect Monster Megalon." But after storyboards and screen tests were done, filming was halted at the last minute, as it was decided that Jet Jaguar didn't have marquee value. But rather than let the film go to waste, Tanaka called in Shin'ichi Sekizawa a few weeks later to write Godzilla and Gigan into the script.
According to several experts (including the late Guy Mariner Tucker), the production time was 6 months, from planning to finish.
I just made a discovery: 6 months was the timeframe of
when it was a Godzilla film!
Thanks to this awesome website:
http://www.cyberkids1954.com/toho_script.html
It seems the actual production time was longer than we thought, as Shin'ichi Sekizawa turned in the first draft (titled "Godzilla Vs. the Megalon Brothers: The Undersea Kingdom's Annihilation Strategy"/"Gojira tai Megaro Kyoudai: Kaitei Oukoku Zenmetsu Sakusen") sometime around September of 1972! (The second draft, called "Insect Monster Megalon Vs. Godzilla: The Undersea Kingdom's Annihilation Strategy"/"Konchuu Kaijuu Megaro tai Gojira: Kaitei Oukoku Zenmetsu Sakusen" was turned in on September 5th) I can guess, based on past data, that the Jet Jaguar film was probably planned earlier in the year, and was probably canceled sometime in August.
If the original Jet Jaguar project succeeded, he also would've been Toho's first superhero, beating Godman and Rainbowman to the punch!
Now I'm really astonished.