[HardcoreZ28]

I've always used a pickle fork to seperate the spindle from the control arms. It will most likely destroy the boot but will be your best option. If you try hitting the top of the ball joint with a hammer you can destroy the threads or mushroom is to much it won't fit through the hole to come out.

I know you don't want to replace the ball joints but you're in there....spend the money to do it now while everything is apart. Upper drill the rivets out and replace with the supplied bolts that come with the new one. Not familiar with the 4th gen setup but I'm guessing you need a ball joint press to remove and reinstall the lower. Very easy to use and makes the job 10x easier. You can usually rent one for like $20 a day. No need to remove the control arms from the car.