Ok, I'm really happy how this project turned out!
Once I found the optimal overhead angle, everything fell into place. That being said, there were a handful of ballparks that for whatever reason would not allow the camera to go where I wanted it to. For these ballparks, there will still be the fisheye lens effect.
With the exception of a few ballparks, I have been able to crop the image to an even 800x600 pixels. I will note those exceptions as I post the sets of images.
My suggestion is that you use these images at 640x480 or 800x600. Anything larger than that and they will become pixelated. I thought about adding a little "blur" to the image to allow for better upscaling, but I think I will leave that possible tweak to the end users. Personally, I like 800x600 so I am all set.
Once I post them all for people to see, I will zip them up and make them available on my website.