This is a good place to start reading… Battery Basics for Beginners Wiki [Serious]
If you don’t want to read and just want a suggestion… to meet your specs, I might suggest a 12S10P 30Q pack or a 12S8P 40T. These are both around ~30-32AH and will get you ~27mi, you’ll need closer to 40AH to hit 35mi of range.
Make sure to upgrade to a metal baseplate if you haven’t already.