67 barracuda with a 383, need help!

And did he happen to pressure test the system for leakage?
He hasn’t pressure tested it yet, but first my heater core went out and then my temp would run to the far right side after 15 minutes. Following that I lost a freeze plug… so started from the ground up. Replacing heater core, pressure testing, sourcing right parts etc. I won’t be getting to it for a minute following an accident but trying to be prepared when I do