Basically the mentioned 300 and 400 grain lines can be easily cast with a one hand rod. This rod should, if possible have no pure specification, because a semiparabolic action eases the usage of the heavy sinking lines. Casting those lines can become rather strenuous in the course of a fishing day, though.

For salmon and steelhead 9-10 feet fly fishing rods, designed for 7-9 weight are suitable. Good to high quality rods are better capable to withstand the loads because on our rivers, your equipment will be pushed to its limits.

A two handed rod makes things simpler and less strenuous.