Nitto Dynamic stems are a good option. They are available in 25.4 as well as the more common 26.0 diameters. Angle is around 72 deg. Quite hard to find, bought some from Freewheel, SF a while back.
Lots of the older ITM quill stems have a clamp of 25.8 which means they work well for 25.4 and 26.0 bars. Have this option working for me right now. ITM made stems with all kinds of drops/angles including track specific stems.