We have a 32' chimney with a insulated 5.5" liner and enough draft isn't an issue. Where problems will be is you will have a bad overdraft. Most companies test with a chimney around 14 or 15 feet tall. You will be more than double that. Contact the company and see what they recommend. Either you would benefit from a key damper in the flue, or a Barometric Damper if they recommend one. We use a baro, but here lately I have also experimented with a key damper. Im sure the company will suggest a key damper. With a chimney that tall, a baro may let too much air into the chimney causing rapid creosote buildup. Burning good dry wood and hotter fires will help eliminate creosote.