"93ish" is not a valid measurement. Sorry. You need to be a real geek about these things and get it right. Use calipers or measure 3x and average the results. If you really did end up with something significantly less than 100mm, honestly I think it would be easier to find a new (or used) 100mm OLD (over locknut dimension) fork that is the same length as the old, than a shorter axle. That being said, have you simply tried putting the new wheel in the fork and seeing what happens when you torque down the axle bolts? I would.