Thanks very much to the folks that helped, especially goldpins for providing the measurements. I wanted to follow-up here for anyone who happens by and in case any of you ever have yours break.
I used a 3/32" stainless rod to make my new gate because it was easier to get than brass (remember it needs to be non-ferrous!). I held the wire in a vice and used a hammer to gently bend it so I could get nice tight corners. I found using hands/pliers ended up with real wide corners.
After getting the general shape, I held the top arm on the back 'anvil' portion of my vice and beat it flat with the hammer, as you can see in the side view pic attached. Once I had it about as thin as I thought it would go, I drilled a small hole in it (1/16" bit was smallest I had) for the spring connector.
I should mention when doing the initial bends, I ignored the angles in the gate and just made it flat. Once I got it all drilled and cut, I put it back in the vice and gave it the angles you see in the picture. Those had to be played with a little bit to get the gate to open high enough (it doesn't move much!).
At this point, the gate opens just high enough to allow the ball to push under it in both directions, the same with it works going under the right gate.
Because the now flattened end is to fat to go through the gate bracket hole, the wire needs to be fed all the way through from one end (right side with hole, not slot), but that wasn't a big deal at all. As you can see in the third picture, the top left "hinge" portion could be a bit shorter to make it easier to get that in, but the wire was malleable enough that you could get it in there, then squeeze it back into shape if you happened to widen it trying.
LeftMistGatewMeas.jpg LeftMistGateSide.jpg LeftMistGateAttached.jpg