I understand that CS is a significantly more popular major than physics and that with many colleges it is an impacted major with major enrollment restrictions. You may want to enter as a declared CS major in order to secure your spot in that major depending on whether the institution does have strict caps on its CS major. But if your major interest is in physics, then I would be much more interested in the quality of the physics program than the CS one. I suspect that the CS major at most universities is going to be perfectly sufficient for most people who intend to go on in physics. If there’s a particular subfield of CS that you’re interested in, especially as it relates to your interest in physics, by all means look at the faculty’s descriptions and course offerings to make sure that university will work for you. But the focus, in my mind, should definitely be on the main field of study you’re interested in.
There are many high schools with Naviance or similar programs that detail what the stats and acceptances/rejections have been at universities from a particular high school. If you look at various threads around here (including the yield protection one or the one on VA Tech EA results) you will see that there have been lots of surprises with people who had very high stats with universities that they think they “should” have gotten into.
Once again, I’d ask what kind of an experience you would like out of college? Doing that can help not only in creating a balanced list of schools to apply to (balanced with respect to odds of admission and affordability), but also when it comes time to make a decision. If you know the things that are most important to you, then it’s easier to evaluate your options to decide where you want to enroll.
ETA: You can also check out the Georgia Tech EA results thread.