Any 98 action will handle a .30-06 by either replacing the magazine or modifying the existing one to make it long enough to hold the .30-06 round. All but the longest cartridges can be handled by just grinding a bit from the front and rear of the magazine. Only the feed ramp has to be recontoured and this does not affect strength.
My Mark X Mauser is a standard length 98 but has a long magazine extending back under the bridge to hold its .375 H&H magnum cartridges. No problems and its plenty strong.
I wouldn't use any Springfield for the basis of a sporter. They are expensive, many sporter parts mostly long out of production, and the 2 piece firing pin is a weak point.
However I have gotten to the point where I will no longer build any sporter from a milsurp. A competent job always costs much more than a commercial rifle of equal quality. If you want a nice rifle trot over to Walmart, buy one and stock and scope it to your desire. It'll be "custom" enough, work better than any milsurp conversion and cost less.
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