Whats the best way to go about removing stock headers off a 289, They are so badly rusted but they gotta come off and im not sure the best way to go about removing them.

 

Unbolt them and take them off. If there's some rust still holing them in place try giving it a few love taps with a plastic deadblow hammer. Just make sure you clean any rust of the heads that might mess up the gasket seal when you replace them/put new headers on.