I'm in the same boat, my Dart is 3350-60 with me in street trim. It's been mini tubbed but that's it. The vents, radio (doesn't work), all heater components and wipers are still it and I'll not remove them to get weight out. The way my car sits now it would easy to put back to stock appearing if one wanted.
I'll never have a car with good power without a roll bar and frame ties. Aside from the safety aspects it keeps you from killing the car. I added 2 x 2 welded in frame ties to mine first and could tell a difference just driving it, the car felt tighter. The roll bar stiffened it more.
At first weight is easy to remove, lighter front brakes, aluminum heads and intake, lighting bumper brackets, fiberglass hood and front bumper and a lot of small stuff. But then come the things that add weight back, roll bar and frame ties, the R block alone was about 60 pounds heaver than the 360 block it replaced. Moving the battery to the trunk adds weight for the extra cable and the necessary components for the wiring. Plus my car picked up nothing after the change.