The Nitto Technomic stem comes in a very long version. Another alternaive would be one of the adjustable angle quill stems. Set the fore part up to around a 60 degree upward angle and then fine tune it with the insertion depth. Or an extra long quill to threadless stem adapter and a suitable mountain bike rise angle stem. This last bit means buying two parts instead of one. And Nitto stuff isn't all that cheap so an adjustable angle longer quill stem might end up being the best way to go.