Advice for Noob with Slant 6 Barracuda

Hi Guys / Gals,

My Girlfriend and I just took her 69 Barracuda Mod Top outta storage. She's had it since college (the 90's) and I'm helping her get it restored / running a bit better. She's got a 255 Slant 6, all stock parts and she feels pretty low on power... not a lot of pick up. A mechanic friend of mine said that the carb wasn't in good shape and he suggested replacing it.

If we were looking at upgrades to get a bit more power out of the car, what would you guys suggest? If we go to a 2 / 4 barrel carb, do we need to replace the intake manifold? What about exhaust?

I maybe over simplifying it, but I guess I'm looking a list of suggested power mods / good things to swap, maybe by priority.

Thanks in Advance!
Drats