Shimano 600 EX crankset - want to change the middle ring

Hello All,

I have a Shimano 600 EX triple crankset (DS arm is stamped with 'FC-6206') with 47-42-26 chainrings. I'm not sold on the 42T ring - looking for a 38 or 39T ring to substitute (if possible).

Two questions:

1) Velo base says that this crankset is 'available' in 110mm or 130mm BCD....