So I wound up deciding on using the i3 in my backup NAS and the Xeon D-1521 in pfSense. The project was delayed by those small missing parts you never think about (I/O shields, power supply extension cable, etc.).
Firewall is now up and running on the Xeon D-1521, the C2758 board is now installed in the Akasa case ready to be deployed at my parent's house, as is the backup NAS which isinstalled with drives and data has been fully replicated.
Forgot to take pics of the firewall swap but not much to see there really. Even though the NSC-810a case is designed for mATX cases, I'm glad I went with Mini-ITX. It accomplished exactly what I wanted which was give me more room to work with compared to the NSC-800 I used a few years back. As you can see I'm pretty terrible at cable management so it paid off.