Getting back to the original question, I checked the cartridge collection. A RWS 8X88S case measures .5205" on the base and .510" on the rim. A Western .30 Newton case measures .525" on the base and .523 on the rim. A Western .35 Newton measures .524" on the base and the rim. 68mm = 2.67", compared to the 2.5" Newton cases, so the 8x68S case is ideal for making .30 and .35 Newton cases.
The 8x68S is about 30 years too young to be the parent of the Newtons. I've heard that the 9.3x64 Brenneke is, but I don't have one in my collection, and Cartridges of the World gives a base of .504", but Firefly gives .524" and I don't know which is correct. It's possible that Newton or Adolph sized down .280 Ross brass. If Newton and his backer hadn't gone bankrupt, we won't need the .300 H&H, .308 Norma Magnum and .300 Winchester Magnum. He was far ahead of anyone else in the USA, and magnum fans had to wait for Weatherby 40 years later.
BTW Donna, I really enjoy your site.
Bye
Jack