I have a '63 Catalina Safari with a 389 that currently has a 2 barrel carb. Can I get a 4 barrel intake manifold that will fit this?

Todd, COOL CAR! Yes, any intake from a '61 through '64 Pontiac V8 will fit. Highly recommend the Carter AFB as opposed to an Edelbrock clone.
If you have difficulty locating an intake, e-mail me. I don't currently have one, but usually know where I can get ANY Pontiac stuff (lots of contacts).
You should go to boyleworks.com/musclecars and tell those guys about your car. classicalpontiac.com is another place you would receive a warm welcome. Those guys love the darksiders (BIG cars),

Jim
cvms@cstone.net