I think I know approx. how many cartoons were in the Cinepix/Astra/Cinema-Vue package, thanks to the Yowp article I posted in the OP.
Seems they started out with about 100, c. Sept. 1955:
"Cinema-Vue Takes Cinepix Cartoons, 1-2 Reel Comedies
NEW YORK, Sept. 17—Cinema-Vue this week took over distribution of the 100 cartoons and 100 one and two-reel comedies that had been handled by Cinepix. It is expected that the Westerns, features and other product out of the latter’s vaults will later also go over to Cinema-Vue, making Cinepix inoperative as a separate entity.
Frank Smith, who had been running Cinepix, has moved over to the new firm as vice-president under his brother, Joe."
A follow-up story in Oct. 1955 says that they now had 150 cartoons on their package, and another article, in May 1956, reveals that they had expanded the library to about 350 B&W shorts, and that they acquired a bunch of "color" cartoons from Morris Kleinerman.
"Cinema-Vue’s New Batch Of 52 Color Cartoons
Cinema-Vue Corp, has acquired a new group of 52 color cartoons, which added to its backlog of 350 black-and-white subjects, brings its total animated library to 402 shorts. It had acquired 150 b-w's only a week earlier. All the films go into its "Whimseyland" package. Of the 52 new color subjects, 12 of which are "Mutt & Jeff" pix, a total of 40 were acquired from Morris Kleinerman..."
Dunno if this means that they had THAT many cartoons in the package, or not, or just generally refers to the amount of B&W stuff they had in their library at the time. A "Sponsor" magazine from Jan/April 1957 mentions 150 cartoons as being in the package...
Also, it seems their bootleg cartoon package put out by Astra/Cinepix had an actual name: "Whimseyland".
"With all respect to the great mousetrap."- Popeye, "The Spinach Overture" (1935)