Good idea on the gauge.

Myself, when it comes to cooling, I have been through this all also. If it were my car, I would:

Confirm temp with a gauge,

Confirm tune

Call Glen Ray and get a factory style radiator built. They will do one without all the date codes etc. so you can save a few bucks there but they are not cheap. Get the right shroud, fan and pulley's . As mentioned, all the places that were sealed from the factory are good to have in place and are designed to make the air flow through the radiator.

If that doesn't do it I would go after the WP housing and run a flow cooler WP.

I run a 496 with the Glenn Ray radiator, factory stuff for the rest other than the flow cooler WP and I ran on the thermostat idling in the staging lanes a couple weeks ago at the track. 90 degree day. I am so sold on this set up that I am using the same thing on the 543 going in my coronet.

Good luck ! Nothing worse than sitting at a light watching the temp creep up, wishing the light would change, the slow driver would speed up, the 18 wheeler could make his left turn faster when you are stuck behind him etc etc.