I wouldn't do anything to the tension bolt; or at least, not yet.

I would first reshape the top. To do that, you have to get it really wet; you want the leather to absorb as much water as it can absorb, without letting any leak out Consider: if you soak it in a bucket of water, the water will turn brown. Trust me, I know this will happen. Whatever that substance is, that is coming out of the leather and going into the water, to turn it brown, it's something that you don't want to take out of the leather. So to make sure it stays in the leather, try to only add water, a little at a time, until the leather won't soak up any more. Let that water sit in the leather for an hour or two so it reaches an even distribution. Once that's done, you can reshape the leather with your hands. Ball up some old newspapers and stuff them inside the saddle, pressing the newspapers into the correct shape for the inside of the saddle, while squeezing the skirts together as much as possible. You should be able to get the saddle back to approximately its factory shape.

Then fold up another piece of newspaper into the longest possible strip, about 2" wide, and wrap that around the narrow part of the saddle and hold it with a piece of tape. That should be enough to hold the shape of the saddle until the leather dries; but it would be a good idea to periodically check on the shape as it dries and correct anything that seems to be going wrong.

When the leather dries, it will be harder than it is now. At this point, if the shackle bolt in the nose is loose, tighten it up enough that it doesn't rattle.

The above treatment is pretty radical, and will make your saddle into something pretty different from what it is now. I expect it will be better, but that's for you to decide. Some saddles, when reshaped in this manner, will hold the 'new' shape for a good long time; others return to the old shape pretty soon.