Monty ....Not as much as should ... my guess would be high pressure build up in the engine bay not allowing the rad to flow freely ... my car runs fine without overheating ... but if it did, my first try would be a short ali floor fixed between the chassis rails to about a third of the engine bay with a 1/2" angled kick down on the back edge to create a low pressure area behind the rad ... then let the underbonnet air bleed out through the louvres and under the car (my car has plenty of ground clearance and the crossflow sump doesn't project below the chassis rails)... as you say, without hard Morgan related data (which probably isn't there) we're shooting blind but I'd try that before anything more expensive.
K
Ps ... I wonder if the GT and LeMans cars saw a wind-tunnel? ... not Trads but would be interesting to see.
