360 overheating -please help

My 360 in my Scamp would stay nice and cool on the highway or pretty much as long as I was moving, no matter how slow I was moving. If I got in traffic on a hot day or went through a drive through or something it would heat up. I had a good thermostat, good water pump, and a "good" stock radiator that was the factory 318 radiator. I put in an aluminum radiator and a tranny cooler, and now the car runs almost cold and never heats up. Simply put, your radiator might not be up to the task of cooling your larger, modified engine. Mine wasn't. That being said, all the posters have given you good advice. All you have to do now is sort it out and get your car running cool.