I agree with the .358 for short action rifles.

I would choose the .257 Roberts instead of the .250 Savage, but with a normal chamber throat in standard length actions.

The 6.5x55 is a hell of a ctg., having the capacity of the 7x57,. but in a slightly shorter case, hence it's larger base area by design to achieve this in the shorter m9496 actions.

In modern actions & using IMR 4320 in the 7x57 and Reloader powder #19 in both:

7x57 - 2,940fps with 139/140gr. & 2,700fps with 160gr.
and
6.5x55 - 2,960fps with 129gr. & RE#19 - 2,860fps with 140gr.

Both, given 22" to 24 bls.