Here is the bspp connector:
http://www.amazon.com/gp/product/B00...2&sr=8-2-fkmr1
here is the stem elbow:
https://www.freshwatersystems.com/p-...-516-tube.aspx
Again, you need enough space to pull this off, in particular to screw on the bspp fitting on to the shank. If you have just enough space, you may need to put the stem elbow in the bspp fitting first, and then screw it on to the shank.
Also, those links were some of the first I found, and you may be able to find them for cheaper prices with shipping elsewhere (especially if you don't want a 10 pack like Amazon sells the bspp fitting as)