Usually the large action (model 98) is used to make the guns for the longer bullets. They generally take more pressure and are used by most custom builders. The short action is not normally recommended for anything that generated a large amount of pressure. I try to stick with a caliber of equal size to the military bullet, and of equal or less pressure when building on a small action. Most of the small action guns are very good calibers for hunting North American game. Some do not require a change of caliber, the 6.5x55 Swed, for example, will kill most anything in North America, I have successfully used it for elk, mule deer and whitetails. I use it on feral pigs, and for shooting yotoes too.
The 93,94,95 and 96 have a front receiver ring dia. of 1 1/4" (that is measuring across the front of the receiver where the barrel threads in.) The trigger guard screws are 7 5/8" center to center.
The large ring (model 98) has a front receiver ring dia. of 1 3/8", and center to center on the trigger guard is 7 7/8 inch. It is called a large ring, long acrtion, and is used by many commerical gun builders to build their guns.