Meeting rail is curved

Hello! Thanks for reaching out to us. Based on the description you give here, it does sound like the sash frame might have been pretty badly damaged after the break-in. I don't see how the keeper would fix anything though.

The meeting rail needs to be replaced but going back to 1999, that will likely be impossible even if you knew who the window manufacturer was. My suggestion would be a complete window replacement. 

To add to what Paul said, I'm wondering if you have a "stiffener bar" that runs horizontally in your sash. Check the rail in the window and see if it could be that the bar is bent. I'm just not sure if you would be able to remove it from the window check rail so you could straighten it out and reinstall it.  

It might be a better fix to install some washers or a type of spacer under the sash lock to raise it up to meet the keeper. You will also need to use a longer screw to reinstall the sash lock after you pack and raise it up. As for the keeper, I believe you would have had the 90-307 in your window. Take a look at the 90-282 along with the 90-307 keeper. See if these keepers could work for your window.