Hey Freak looks like the radiator may have fixed it.
Just something to note on extremely rapid temp increases. I had a gripe exactly like yours, and replaced almost everything you did. I could start -up the car and with my radiator cap off could actually see the coolant flow when my thermstat opened up. And the thing still heated up almost instantly.Very frustrating.
It turned out to be a pin-pick hole in my retun heater hose. The dang thing emitted a silent and fine steam mist and evorporated immeadiately leaving absolutely no evidence of a leak-it also did'nt do it at idle,though the engine still immeadiately overheated. I only caught it by jumping out of the car quickly after a short test drive and popping the hood.