dyno numbers from my 340 just for reference

Shroud will help more in the city . Did you check the cap , maybe the thermostat is bad ? Should not run hot on the highway . There is a rubber gasket under hood up near front , do you have that on your car ? Think it helps keep air going to rad instead of over it between hood and top of rad tank, every bit helps
Ran my car in city and highway yesterday , was 95 degrees ran cool ,almost same setup you have except the shroud , stock rad and clutch fan ,190 thermostat , do you run plain water or mix of anti freeze water ?