Basically, the joint diameters of the cues haven't changed tremendously since the days of George. They'll pretty much come close to 835 to 850 thousands of an inch, give or take a bit. I've seen a McWhorter that was slimmer, but that was an exception.
The difference is how they taper to the buttplate. The older cues had a steeper taper to the end of the buttplate. The biggest buttplate in my collection is my Palmer Model C, at 1.28 inches. The others, Scruggs, Black, etc, are about 1.25 to 1.26 inches. Not a lot of difference, is it? But it is in your hands. And the older Bushkas were no doubt a bit thicker in the buttplate, but I think we're talking several hundredths of an inch, not something like a quarter of an inch.
Except, I will admit, a Rambow Tim Scruggs showed me in the late 70s that he had gotten for repair/refinish. Normal joint diameter, and the buttplate looked and felt more like a Louisville Slugger than a cue, it was so big in the back. There was some variation in the early days.
A few hundrendths of an inch feels major in your hands. For example, in the middle of my wrap areas, my skinniest Scruggs Titlist conversion is 1.09 inches. The largest in the collection is 1.13 inches, a 1976 Joss. Feels like the difference between night and day. And it's only, you guessed it, four hundredths of an inch.
Get your micrometers and dial calipers out. The differences feel pretty major in your hands, but they actually measure smaller than you might think. Assuming you don't get your hands on one of those Louisville Sluggers...