My 78 with a bone stock L28 started overheating.
Radiator had a big crack, which is probably why it overheated.
So I replaced it with a Koyo S13 SR20 radiator, and removed the thermostat because I suspected it being clogged. This was just a temporary solution until I could get to a parts store to get a new thermostat.
However, I've driven it to work since then, and it WON'T get above 130 degrees. Driving, it goes right above 120, and goes to about 130 at stoplights. And it doesn't even have a fan shroud.
Any opinions why it's doing this, temp sensor is good, plenty of coolant.