just a normal fan.
You need to move your fan enclosure onto the actual carriage otherwise the arms will clatter into it.

You basically have the space between the hotend bolt heads and the edge of the gap to place both your fan and the shroud. The duct can go down between the arms, but even my 25mm fan is much too wide to sit that far forward.
Which is why it's actually easier to redesign the carriage with the fan clip already in place than try and make something to attach.
I'm also thinking about the fan and duct just slipping over the top of the fan and clipping into place somewhere (there may well end up being tiny cable ties involved :-)

Currently being mulled over in my hind brain, which does all the hard work :-) Also need it to print without supports, 'cos I've never designed anything that needed supports yet and don't intend to start now :-)
I also want it to look cool, so some organic curves wouldn't go amiss.
We'll see.
One option was to make the duct and shroud out of polyflex, so i can bend the duct into place.