I think a .308 win case shortened and sized down to the deminsions of the .35 Remington would be very useful. The new case would be slighting larger in diameter, but otherwise it would have .35 Remington dimensions. The advantage is the case could be made from any .473" diamter centerfire rifle round, 308, 30-06, 270, 7x57, 8x57. It would not be able to be chambered in a regular .35 Remington rifle because it would be too big. Although it would have a slightly greater volume than the .35 Remington, it would not be significantly more powerful. Bear in mind, that more power is not the objective. The objective is to get a .35 cali lever action round that is easily formed from cheap, widely distributed casings, unlike .35 Remington brass that is sometimes difficult to locate.
.358 Winchester rounds would not chamber in it so there would be no danger of accidentally loading a full powered .358 win round.