Waterless Coolant

I too had chased an overheating/runs hot issue in my A body.
While the rad looked ok, I also opted for a nice mopar clutch fan, shroud, flush and even added a pusher.
The fix was in the radiator itself, as the original rad had enough scale build up it just wouldn't cool at idle or constant high freeway speeds.
You didn't mention how old or what condition yours was in, and if originality is not a problem there are plenty of cheap aluminum ones.