from center of seattube to the inside of the crank arm, at the tip, i have 52.5mm. ( that's on a 111mm campag square taper bb, i assume the sugino would bring it inwards by 1mm each side ).
It's coming quite close to the chainstay so i can't really go any lower.
i have a sug 75 + bb i might be into swapping for a change. my frame is steel too though so not sure about chainstay clearance.