What's the reasoning behind him "needing" a noseband? If you are thinking of using one to keep him from gaping his mouth, then you would essentially be taking an aspirin for a broken arm. Sure, it may cover up the symptoms for a short time, but it won't fix the problem.
Generally speaking, a noseband (or caveson) isn't a standard piece of western equipment. The folks that do use them
properly only do so for decoration and they serve no real purpose.
Or are you talking about a tie-down? If you are wanting to use a tie-down on him, it's pretty unlikely you'll ever be able to go bitless because he'll learn to brace against it and won't associate pressure there with the cue for stop. Plus, tie downs are not for creating headsets. If it's being used to keep their head down, then it's being used wrong and causing many more problems than it will ever fix.
If you are wanting to go bitless for western riding, I would strongly suggest either a sidepull (avoid the single rope, they are rather harsh)
Saddles Tack Horse Supplies - ChickSaddlery.com Leather Stitched Sidepull With Double Rope Nose
This one is full leather. It's technically an english bridle but you could switch the reins out and it would work fine for western
Tory Leather Nose Side Pull - Horse.com
Or maybe something like a soft or "loping" hackamore. It has the functionality of riding in a halter type bridle, but has the look of an actual bridle.
4 Plait Soft Rope Hackamore w/Flat Reins | NRS - National Roper Supply - Western Wear, tack, team ropes, horse tack, team roping ropes, bits...