Are you sure the crankset isn't a Sugino
GT? Seems that's what (sometimes) came on Fujis of the era. If it is, it's got a 110BCD, and the smallest chainring for that BCD is 33. The quickest/simplest thing to do is ditch the 52t chainring, put the 42t on the outside (you
should be able to just flip it so the inset for the chainring bolts are on the outside) get a
33t, 110BCD chainring and put that on the inner position. You'll have to lower and readjust your FD. Eliminates having to change your BB/spindle, etc. It won't get you
super low, but it will get you lower.