Mine is lifting in the middle on the 75 H/O, I assume rust is under it, can you even get these replaced? Or should I just tear it off and paint it black?

 

That's pretty common on the Hurst tops. They can be replaced- any good auto trim shop should be able to do it. Finding the correct material may be a challenge.

Top cover ballooning up is not always a sign of rust underneath, although the way the tops and their trim pieces were put on it would not surprise me to find it.