Cletus, I use a six core rad without the shroud, I think it would make a big difference to include it. KPM might have more experience though.
A nifty cooling retrofit at home here has a marine background. The keel cooler concept under boats has been copied on a Narrow Gauge with the 300ci Ford Six.
With the original radiator in place, a splice was created and 3/16's boxed steel used. With a return loop, it is mounted underneath along the drivers side with cooling fins attached.
The 13 litre capacity became 28 litres and runs a 195 thermostat. Works sweet! There are probably many applications to the idea, adding coolant capacity under load is the ticket every time.
This unit is away currently at work and will be nearby this March. I can provide a phone # if you like and will post pictures when it returns.
David