Ben's Cycle has Profile MTB stems, 25.4 mm HB, 22.2 mm quill in a variety of rises and lengths.

Ben's Cycle - Stems[Bar%20Clamp:25.4^$Quill%20Diameter:22.2]&PriceMin=[2.2500]&PriceMax=[415.0000]&PriceStart=[2.2500]&PriceEnd=[415.0000]&PageNum=[1]&SortBy=[Price%20ASC]&ItemsPerPage=[60]&View=[GridView]

Their site makes finding stems easy. You can sort by faceplate, bar diam. and quill diam.

And, no, I do not have any affiliation with them other than buying a stem or two in the past. They have been straight up to deal with and carry good stuff so I would again in a flash.

Ben (Ben's Cycle opened a few decades before I was conceived.)