Need help on first time rebuild 318!!

I really couldn't put enough stress on how true this statement is. You're going to want to upgrade to a stronger rearend, not just a new set of gears, assuming of course what you have in the car is stock.
the car is all stock right now with a 273 still in the bay i was planning on putting a bigger rear on it but not sure what yet still doing research and talking to people who know stuff.