legend, there are lots of ways to make this a tasty roast. If you want to sear it, then do so. But you don't have to.
If you want to cook it at 400 or 325 or another temperature, go for it. You can cook the roast properly at more than one temperature.
Don't stress out, do what you are comfortable with and enjoy the day.
"If you want to make an apple pie from scratch, you must first create the universe." -Carl Sagan