Dura-Ace made a sealed NJS square taper BB, they are quite hard to find. I have one on my beater... Hold up I'll try to find a photo.
"**Pictured below, the 7610 bottom bracket is the match for Shimano's previous generation track crank: the 7600 series with traditional square spindle tapers. Available in English or Italian threading (the English one is Keirin approved), it has a symmetrical 109 mm. spindle and sealed cartridge bearings"
And the taper is...?