Feel like my 440 should be faster

I have two thought as to what's causing the sluggishness.

First off is the heads. Bolting a set of unported stock heads to an engine with that size cam is never going to result in decent power. The stock heads have a lot of room for improvement. Just a little bowl work will go a long way. Add in a bit of milling, maybe .025" is so, and you'll get a much better setup.

Second is the vacuum secondary carburetor. It's entirely possible that the secondaries aren't opening all the way. Make sure to check what spring is in the vacuum pod. Anything other than the second lightest available might not allow full opening on a mild build.

As for cam size, I've looked into that cam. I like it for the most part as far as creating a nice, torque oriented engine. It's just limited by the cylinder head. I've seen the 452 head untouched first hand. I would not recommend it.

The 3.23 gear is hindering you a bit for sure, but your cam is a torque cam. I would only worry about swapping gears if you want the car to be more strip than street.