I only know World's Greatest Chillers from the ads and listings you see here. These are from around the same time that KGO ran Chillers From Science Fiction on Tuesday afternoons, and appears to be the same film package.

What's notable is that the show is on late, is a double feature, and was also advertised. A lot of late-night unhosted horror slots over the years were used to fill dead time when ratings were so low that breaking even was the station's only hope for the time slot. These shows were never advertised in the TV Guide. And yet, KGO seems to have been making a big deal out of World's Greatest Chillers, the ad above even tries to build anticipation by announcing the show a week in advance.

Whatever KGO's intentions for the show, World's Greatest Chillers had a very short run. It began on Saturday, 2 November, 1963, but on 14 March, 1964 KGO had a western in the slot.

Interestingly, World's Greatest Chillers coincides with another late-night horror show at ABC affiliate KOVR-13 in Sacramento. There's a listing for THE GIANT GILA MONSTER airing against KGO's ATTACK OF THE CRAB MONSTERS on the left. I'll have a page up for the KOVR show shortly.