model A overheats

[wagonshed]

Looking for suggestions on what to do next on my "29 model A speedster. When the air temp is approaching 80 degrees the red of the temp gauge is in the gauge's circle. Temp of high 80-90's she'll boil over. Engine was rebuilt perhaps 10 years ago, newer leak proof water pump, checked timing and carb adjustment and cleaned radiator with permatex radiator cleaner twice. Don't know age of radiator, any suggestions other than replacement? Thanks