TA 340 6 pack in a 68 Dodge Dart vert

Do you have a fixed fan on the water pump? You could really really! Use a viscous fan on front. How old is the radiator? Is the radiator a V-8 radiator? I swapped these things out on my wife’s car along with a report shroud like you have, and it dropped the temperature, a lot!

What’s the compression ratio and where is the distributor set up? Is the cam stock?