You can add an aftermarket temp gauge to tell you what's really happening. If it really is overheating (temp over 220F or so), there could be many causes and all of them will require some work. The radiator could be clogged, the water passages in your engine could be clogged, or your water pump might be rotted out or not assembled correctly. Not sure of the condition of you car and whether any of these are likely or not. My friend's 68 cougar drove him nuts with overheating and he finally took apart the water pump and the impeller was rusted away and not functioning. The 455 I procured for my goat the water pump was missing the rubber sleeves. Somehow it still functioned enough. I could see the missing sleeve when I removed the upper hose.

The bubbling and gurgling after shutdown is no big deal. The heads are hot and the water is just sitting in them and not circulating.