Correct PSI Radiator Cap for '70 340?

got my first radiator recored around 1985. The shop (which did nothing else) told me to use a 7 pound cap. It worked with absolutely no problems so it's what I've used on all our Darts for the last 35 years. Like #67Dart273 says above, less stress on the whole cooling and heating system. The car that shows in the "stock" class has a factory 16 lbs cap in the glove box that has never been under pressure...