A properly sized and fitting shroud helps air movement immensely. The fact that the truck didn't have one doesn't mean the car shouldn't have one. The cowl hood does help reduce underhood temps as it provides an easy path for underhood air passing over the radiator to escape. Because of that, it may also allow for more air to pass over the radiator at speed. Go drive the car - even revving the engine puts very little additional heat into the radiator. The engine has to work to make lots of heat - and it's not working hard at all sitting still. Let us know what happens when you drive it.
i do have a shroud in the car. look at the link in one of my previous posts. it shows the radiator and the shroud. the fan runs directly from the water pump. it is a stock flex fan from an 82 truck. it has a long spacer to get the fan less than 1 inch from the radiator. the shroud is from an 87 gt.
Yup - saw your mention of the shroud in the first post; others besides those of us engaged with this one read the threads. Didn't want anyone to get the idea that just because it worked in your truck without a shroud that it would be ok in a Stang without one. Your previous post seemed to imply that - didn't want to mislead anyone else.