395, 36, 44, 89, and that will take you north of Shasta Mountain, towards the city of Mt Shasta, I 5, then north towards Weed, then take I 5 all the way north to Portland.
Just don't fill up with fuel in California, if you can possibly avoid it! Especially Susanville CA, just look at the prices there, and laugh at the people who live there and pay well over $4 per gallon!
While a lot of the highways are two lanes, and not to frequent passing lanes, the distance between Reno and Mt Shasta (the city) is not that far, and very scenic. So if you 'have' to go slowly someplace, this would be a great place to take in the sights!
It also saves driving all the way to Sacramento, and cuts out about 100 - 150 miles, so you will more than make it up in time saved as well as saving fuel costs.
Fred.