Russ,
The repost shows much better whites in the lower half, but you've applied the changes to the entire image, and I think it's now a bit bright overall.
Apologies if this sounds like I'm nit picking here, it's not meant to come across like that, but I just think this image is so strong it just needs that final bit of polish.
Here's a screenshot of what I did. I appreciate this is photoshop and you're using lightroom (which I don't use) but I'm sure there is a similar way of doing things there using the adjustment brush to target specific areas.
If you first look in the left hand grey box, which is the curves box, you see the data on the histogram is quite a way off the right hand side, and with such white birds, this means there is a lot more detail to be had. The box shows the adjustment I made, which was dragging the tiny white triangle just below the histogram from the bottom right corner towards the left a bit, and it's now nearly touching the edge of the data. That had the effect of brightening all the image.
Next, look at the first grey box to the right of the image - the layers panel. There is a layer called 'curves 1'. In that layer is a box which is mainly black with some white at the bottom, thats the layer mask which is automatically created with a curves layer. The run in photoshop is 'white reveals, black conceals' so the white areas in this box are the only areas affected by my adjustment.
Now, you can't exactly replicate this in LR, this shows that I only targeted the lower portion of the shot, and in lightroom you could do something similar. You might be best googling this, but from memory, if you clicked on the adjustment brush, brushed over the areas you wanted to target (similar to my black and white box in the layers panel) then made an adjustment using the highlights slider, then you should end up with a similar result and keep your detail throughout.
If you look in the far right hand box, you can see the histogram now covers most of the range without anything being blown, and a full range of tones.
I hope that makes sense, just trying to finish off this excellent frame.
Mike