Radiator/Engine temp questions

SFBay‘72Duster said
The thermostat is a good idea for sure. I’ll get a temp gun too.
Im wondering if my radiator is too small. Maybe it’s for a 318 or 340 only?

Who knows? Maybe get the dimensions and post them, including how many fins per inch and how many flues and how big they are. That'll tell the story real quick.