Why pair high speed deltas with thermochills? Does not compute. The PA series wasn't designed for that. A hardware labs GTX radiator is what you should be looking at. But even on the GTX you are going to have diminishing returns at those speeds. Is the computer going to be in a different room from the monitor and keyboard? Are you just planning to bench with this setup?

As for the shroud, I'm not even sure they are available anymore. Unless you plan to order direct form Thermochill in England. I am currently making a shroud myself using 1/8" plywood, a 4 1/2" hole saw, and 1/2" x 1/16" inch aluminum bar for making L brackets. Be aware that the consensus at the moment seems to be that pull/pull is a bit better than push/pull. Seems like pull/pull or even pull/pull/pull with a 4" deep shroud (to avoid the hub shadow effect) would be a nearly ideal setup. The Thermochill shroud is only 40mm deep and I am skeptical that that is enough to avoid the hub shadow effect. So it is probably better to make your own anyway. I'm not sure what you mean by a slope on the edges and I can't imagine why you would want anything other than an airtight box with perfectly straight sides for your shroud. Another problem you may want to think about is your shroud seal. I'm having a bit of trouble with that myself