Weird timing. I was just browsing sixgunner.com the other day and found an article about a marlin that was blown apart after shooting a few thousand maximum pressure loads through it due to metal fatigue. Unfortunately the site seems to under construction right now and I can't give a link.

I would leave it as a 30-30.
I don't know too much about the .358 win (isn't based on the .308?) But the 35 remington won't offer you anything much in better performance and the ammo will be much harder to find.