vintage trek bb question

Have '85 or thereabouts trek 400 project w/68mm bb & 125mm rear
spacing and would like to apply a used shimano 600 crankset that I
picked up on Ebay. The crankset carries FC-6400 via Japan markings as
well as RK and 30. The existing crank is a Sakae, which needs
replacement and I no longer have the original bb. LBS sold a me a
Sugino bb-sg 75 that carries markings 1.37x24t "track standard
finish" 68-109, which positions the inner ring pretty much in full
contact with the chainstay. I have tried spacers to move the bb to
the right but that doesn't allow the crank to push fully onto the
spindle because the bb shell has affectively been elongated and the
entire length of the spindle taper is no longer fully available. My 2
questions: (a.) Wassup with this Sugino bb? What kind of a crank
would work with it and was it meant possibly for a track frame? (b.)
Is there a shimano modern sealed bb that will work with the 600 crank
and this frame?