Overheating problems, new to rotary.

[Kfunk1989]

This is my first experience with rotaries. I recently purchased an 86 RX7 from a guy who had been fiddling with it for the last few years, where it had been sitting in his shed. It has an overheating problem, and after getting the coolant flushed and thermostat replaced, it overheats even faster than when I bought it. After letting it idle for around 5 to 10 minutes, I drove it around the block and when I got back home, the temp gauge was at the top and I could hear a slight bubbling in the engine, and some coolant had backed up into the overflow resivour. Im thinking that I might need to replace the radiator, the water pump, or both. Any suggestions? Should I take these steps, or is my engine totally shot?

Thanks.