Last time I was over those roads.... they were paved, except in a couple areas that were washed out and only re-graveled. There was one bridge that had washed out and the replacement bridge was one-lane (no lights, stop and proceed with caution). Both were rough, lots of poorly (or not) repaired pot-holes, broken shoulders, etc. Those roads took a lot of flood damage a few years back and the region does not have the $$$$ to repair them properly.
I have taken a 24ft 5er over that road, with few issues.
A friend talked his wife into going with him over that road, talking about a "stop at Mt Saint Helens", then he decided he was running too late (due to a detour to see something else he wanted to see), so he took the road at the fastest he could in his rally modified Miata. He regretted that for some time.
In general, I would take the Interstate.