overheating issues

Well before we start throwing parts at the car, make sure you've got the cooling system bled properly.

Like mentioned, make sure the radiator is the highest point in the cooling system. With the engine off and cool, remove the radiator cap and fill it with the proper mixture of coolant or whatever youre going to run. Start the car, leave the cap off and let it warm up to allow upper radiator hose to get hot and pressurize. If theres air in the system it'll escape through the radiator cap (you'll notice the coolant level will drop slightly). Shut it off and let it cool down, then top off the fluid if need be. Repeat the steps just for good measure then put the cap on and see if the problem is still there.

Leave the 180 tstat in there. Not running a thermostat will make the engine overheat and using a 160 tstat will just be a bandaid, plus engines aren't efficient at those low temperatures and it'll wear alot faster. I'd even consider replacing the high flow tstat with a normal one. Either way it may be a good idea to take it out and make sure its opening/closing correctly. If its rated at 180*, thats the temperature that it will BEGIN to open and should open fully about 15* higher.

Also if youre running too much timing advance and/or running too lean that can cause overheating as well. I can't help you on the figures you need for your EFI system but a basic rule for timing/fuel is a cold engine needs a little more timing and fuel. The warmer it gets the less timing it needs and you can start to lean it out a bit for maximum efficiency.

Thats where I would start out at since none of that will really cost you any money, maybe just a little time. Also make sure your water temp gauge sensor and cooling fan sensors are near each other and near the thermostat for the correct readings.