Another idea is could purchase a coolant pressure test kit off Amazon. I bought one because i thought smell coolant and was wondering about new heater core i installed. Turned out just residue left on top motor below intake, cleaned and smell gone. Anyway you could pressurize pressure test coolant system and see pressure/water drops just be careful not push water into cylinder if head gasket leaking...
My test pressure 13 psi dropped less 1/2 a psi in 6 hours ...that could be from coolant cooling down and hoses expansion.