A question; you mention the action is a smallring 98. There are such things in several different action lengths. The action LENGTH may help you decide. A full length large-ring 98 action will take the x62 in full factory overall length but a Swede 96 will not, and some other SR action lengths may not. It is possible your action might not be quite long enough.

Small-ring 96 actions will not handle all standard factory length cartrdges. If you have an action of less length than a German K98k stick with the 9.3x57.

The 9.3x62 is a great cartridge, a world standard and you will rightly probably here lots of praise sung about it here. It deserves every bit. It is a great cartridge. I'll leave it to others to comment on.

The 9.3x57 has alot going for it.

I have two right now. One, a 1939-made Husqvarna M146 built on an FN 98 action and the other a 1942-made Husky M46 built a 96. Five rounds fit in the magazine of either.

The 98 will allow bullets to be seated out quite far and in any case will not require bullet bases to be seated below the neck. This allows maximum case capacity and in conjunction with proper leade, maximum velocity.

There are factory loads available for the x57 but it is more or less a handloading proposition, which is no disadvantage as far as I am concerned. To the contrary, it might be an advantage. Cases are the cheap and plentiful 8x57's and in my rifles handloading requires no work other than running a 8x57 case thru the Hornady die and loading. Simple as that. No fireforming, no additional necking steps, nothing. Technically, the x62 has a different case head size than the standard .30-06 size so you may want to stick to x62 cases instead of making them from '06, etc. if yu go the x62 route. Lots of guys report using '06 cases without trouble, but you decide.

My pet load pushes a 285 grain bullet at 2100 fps. I do not know what pressures are generated by my loads, but IIRC, Norma {see their website} lists loads in the 38,000-to-45,000 cup range. I've held my loads to the 2100 fps speed, though in a strong action I suspect you could go higher. If my loads are hovering in the 40,000 cup range, I suspect quite a bit faster. I don't know.

I've shot whitetail deer, black bear, US elk/wapiti, coyote, little varmints and a big half-ton crazy steer at ranges from 10 yards to 200 meters with my x57's and I have absolutely no complaints. There are lots of bullets available for the 9.3 caliber so you would have no trouble keeping yourself busy developing loads. I even draw .375 caliber bullets down to .366 diameter and use them from time-to-time, among other things.

Recoil of the x57 is very mild. Very mild. One of my rifles weighs 5 1/2 lbs and everyone who shoots it comments at how light it kicks even with the 285 grain bullets. Why? I do not know. I find the 8x57 with various loads to be a sharper kicker than the 9.3x57.

And there lies another advantage of small-ring x57's; they can be built VERY light. I cannot imagine a better hound-hunting blackbear {or European dog handler's!!!} gun than a 6 lb, compact-scoped 96-actioned 9.3x57. Mine sports a Swedish jaktdiopter peep rear sight, but my bear houndsman friend has greedy eyes on it anyway...

Sounds like you have a fun project going. Let us know how it all works out!!