A shroud will help a puller fan get good flow but if you look at any modern car's front section you will find air ducting both for the brakes and also for ducting air into the engine bay itself. The Jaguars and other old cars did not face the stop and go traffic of today and to me what is really needed is a way to replicate what modern cars have to duct air in and out of the engine bay. What I found is an air scoop under the valance that directs the air in and around the engine and then by opening ports on the inner fender wells near the firewall good flow can be created which greatly lowers the engine bay temperatures. My radiator with fans was plenty to keep the engine itself cool but the engine bay slowly increased in temperature especially in stop and go traffic to the point it vaporized fuel and caused other issues even though the engine was cool, the with increased stop and go eventually the engine would get too hot as well. The real issue is the venting of the engine bay NOT an issue solved by a radiator regardless of shroud or not.

 

Agree with Primaz, the Mk2 engine bay is a great heat sink, there are no vents taking cold air in or hot air out, and most of the cold air flows directly under the car.

The Mk2 came with a shroud, and it does make a significant difference, but a good electric fan will shift a lot more air than the original fan ever could, so a good high CFM electric fan without a shroud is still better than the existing fan with the shroud.