@DDOPWD23, I'm really confused about the 12.5" size. What is the model number? Pics may help.
Anyway, Atlas had 12.75" and 15" drill presses (were there others? I dunno.).
King-Seeley had 12.25", 13.5" and 15.5" drill presses.
(The '46-'55 Craftsman catalogs say the large drill press is 15". Don't believe it, they are actually 15.5").
(K-S also had the mohawk dp.
The VM Photo Index shows those in 12", 13", 13.25", 13.5", 14", 15". So who knows wtf happened there.)
Regardless, I don't have much experience with the smaller Atlas dp, but a comparison may be relevant between the Altas machines and the K-S 13.5" and 15.5" drill presses.
Because of the smaller diameter column on the 13.5" K-S dp, the lock cylinders are closer together than on a 15.5" K-S dp. Therefore, the bolt portion on the lock handles are shorter by 1/2"(?). The ball-end portion of the handles are the same on the 13.5" and the 15.5" dp.
The lock cylinders on both the the Atlas and K-S DP's are the same length and diameter (except the head lock cylinders are longer on the K-S machines.