Water Pump/Radiator Questions

I would take your radiator to a good old school radiator shop and have it flow tested. It will more than likely need to be rodded out. I just took mine that I thought was clean as a whistle to a shop only to find out it needed cleaning. Made a BIG difference. Also I drill a 1/8" hole in the flat part of my thermostats before I install them. This prevents a air lock. Iwas taught this by a old mechanic years ago.