Check for debris in front of the condenser and radiator. I would flush the system and check the thermostat. The LT1 uses a special thermostat, make sure someone hasn't replaced it with a regular one. When you refill the radiator make sure to bleed the air out with the bleeder screws. Check the overflow hose and make sure it is connected to the top nipple on the radiator just below the cap. The lower nipple is for the steam pipe. There have been several posts about people having them reversed. If they are connected wrong, coolant will be forced into the overflow tank, and it will overflow.

If your gauge is accurate the needle will move between about 1/4 and 3/4 in normal operation. If your a/c was working the fans would come on with the a/c and there wouldn't be as much of a swing in temperature. I lowered my fan on temperature to 212 degrees for the first fan. It just keeps the temperature more consistent without the a/c on. I'm using the stock 180 degree thermostat. By the way the fan temperatures are in celsius in Tunercat.

 

I pulled off the radiator support and found alot of sand in there, blasted it all out with a water hose. Checked the overflow hose and it was connected to the top nipple. I had already replaced the thermostat with a OEM one from the chevy dealer down the road. I did replace the radiator cap also. After doing all this during the morning. I got int the car to start it and..

Miss miss miss miss pop miss pop.. for about 30 seconds. Guess I got a head gasket during that drive the other day when it puked out the reservoir. After it cleared up tho, it cycles about twice at the 1/4 mark on the gauge, then started to increase temp to almost red before I shut it off. My last guess is is a clogged radiator seeing as there is no air in the system and I have just about replaced everything else.