The experts are all over the place with this, and there’s some evidence that a protein cycling approach is better: high sometimes, lower sometimes.
But I always use the gram-per-pound-of-body-weight rule of thumb. That’s your starting point. That’s easy to do to given that you need 800 to 1000 cals over maintenance for good mass phase that doesn’t lead to excess fat gain. If you hit that then you can pretty much play it by ear after that, ebbing and flowing with difference amounts of protein.
There’s also a big difference between types of protein. As Thibaudeau has said, “10g of casein hydrolysate has a more profound anabolic effect than 30g of whey.” So there’s that to consider. Maybe a person wouldn’t need 350g of protein per day if he were using a better source for much of it? Something to think about.