another 360/408 over heating

Dana67dart, I probably mislead you a little. When I say no build up of pressure I'm talking blow out pressure where fluid is pushing out all over the place. I don't even get anything expanding into the over flow.
This morning when I went out and I pulled the cap after it sat all night. There was a very slight suck sound from vacuum from the coolant. I'm sure that was from the hot expansion while running then cooling overnight. And again I'm talking very slight sound but enough to hear.
Here's a question/thought.
This engine has a roller cam so I didn't have to do the higher rpm break in as you would do with a flat tappet cam where everything gets superhot. Could there still be that much friction in the engine from all new parts and if I took it for a 50 mile drive maybe the heat would go away. Should I let the temps go higher and see what happens?
Just a thought.
Thanks Rod