Engine overheating

This is my 2 cents worth. You have a good chance that the radiator has corrosion built up in it unless someone has cleaned it in the past. If it were my vehicle I would put a thermostat in it and get rid of the fan clutch and put a black injection molded fan on it . They cost about $50 plus spacers. Put the fan roughly 1" away from rad but no closer than 3/4" from rad. One of your problems is air flow. So start with the cheaper fix . You will have to change the fan eventually any way. If this doesn't solve the problem providing you haven't done engine damage from overheating then pull rad and bring it to a rad shop for them to look at it. Just my 2 cents worth