Guys do that with .22-250's they pick up with standard necks and they want to make fitted or tight neck cases for them. They use .243 or 6mm brass, to achieve a tight neck scenario in a chamber that is normal for the ctg. They still turn necks, to get that tight neck, or fitted neck condition.

In your situation, using the longer, thicker cases will automatically give you a thicker neck wall - somewhat. The .35 Whelen will likely give the thickest necks when shortened and necked to hold a 9.3" bullet. THEN using the 9.5 dies MIGHT squeeze them tight enough to hold a 9.3 bullets.

It's to bad there wasn't a 3", .06 case.

9.3x74 brass would work, perhaps better, perhaps not, but you would have to turn off the rim, cut/turn a new extractor groove, trim to length and size.