I think
Archway Angel is better than the gargoyle. Gaining life keeps you in the game when you are this slow of a deck. Similarly, I would want 3-4
Plaza of Harmony for the life and the untapped multiland. Not a huge fan of
Gateway sneak, just seems like a bad attacker.
Take those with a grain of salt, I tend to play gates as a slow build: ramp as many gates as fast as you can, then start dropping bombs like 2 Colossus or Rams. Mass Manip is nice, but you don't really have much ramp, just the 4
Growth Spiral. Hopefully it isn't too slow