The Schilke 13A4 with a 24 drill or larger would be my choice. I not a fan of long & restrictive backbores, small drill holes,and tight throats. A shallow mouthpiece will not increase your range, it can hamper lip vibration and limit your range if carried to the extreme. The "correct shallow mpc." will make playing the high notes you already have a little stronger and more secure at the expense of your mid & low range.