Hi shauna wager
I definitely recommend joining the Marketing Cloud Partner Group. As a partner you have access to the documents and workbooks within this group. There are new B&D workbooks, as the packages have changed recently as well.
Also, within that group there is a link on the right hand side under "Deliver IT" that gives you access to a group of really helpful deliverability best practices which I think will help in your discussions. I think regardless of volume a dedicated IP address gives you full control vs on the Shared Range you can't control the sending score. Although our team does it's best to monitor and ensure that we maintain a score over 90 you still don't have control. Also, leveraging not only the IPs, but the DKIM signing and other components included only helps to improve deliverability as well.
Regards,
Victoria