89 Camaro overheats

I bought this camaro a year ago and although i've always wanted one I beginning to hate this car. It has a 305 V8 TBI engine. Love the way it sounds as I drive it though. This year I was in a one car accident and had to replace the rear end differential, the struts in the front the brakes etc. But since the accident it over heats and i've replaced the thermostat, several times, the radiator is brand new, the temperature gauge, the relays an the fan and its motor and its relays for the a/c and had it charged although it is unhooked due to the fact the a/c compressor is trying to go out. I drove it for a month or so with no thermostat but it still would overheat. I finally put in a new thermostat and gasket myself this weekend and it runs fine no leaks etc for about 5 minutes....then it overheats. Everyone tells me that I have a blown head gasket but besides it over heating there is no actual signs of a blown head gasket.

Any Help/suggestions would be greatly appreciated
Thank You

You say your car was in an accident.......is the lower air dam in place under the front nose....that air dam forces air up to the radiator.....

Actually no its not. Its never been there as far as I know. And i cant seem to find one to order. any ideas....