You sure need to address your overheating problem. This is one of the the old timers are not forgiving. I think it would be money well spent taking your radiator out and taking it to a reliable radiator shop or possibly recoring it with a thicker core. Does it have a fan shroud? If not you should consider getting one or making one. I see you were in Austin. I have been in Fredericksurg all my life and operated trucks 45 years. All the things you mention above except possibly timing will help your performance but are not the cause of your overheating.