could the intake be holding my low end down?

3.55’s and what size tire?!?!

Not what I would call and ideal combo myself. Even with stock sized tires.

First order is what Locomotion & Wyrmrider were getting at. Dialing in the distributor timing, then the carb tune. Getting a good and high vacuum reading should be easy enough with that OEM cam. After that, Locomotion’s idea of a 4 hole spacer is a good idea. They help deliver a little more torque.