The car will drive like brand-new, replacing the engine has NOTHING to do with anything that you will feel or detect behind the wheel. If you had a bad collision, that's where you start wondering if "it'll ever drive the same". Get an appropriate loaner, and have faith in your service department. It's not a good situation, but it's one that you can only make the best of. Sometimes sh** happens. If you kneejerk your reaction, you'll jump into a different vehicle and instantly realize that it's not half the car or the enjoyment that your 911 was. So gut it out for now is my advice.