i beleave that it is 3kilos is the max u aloud higher or lower, they are not alound to be to bigger weight difference for the safty of the boxers,
i have personally been miss matched before on my first fight , it was the lad 7th bout and my first , i weighted in at 71k and he weighted in at 74k giving him weight and experiance advantage, i though my heart out that night giving it every thing i had , got hit by sum Big body shots that made it extremly hard to breath in the first round but i kept fighting by the third round i was dead on my feet got hit with 3 strong uppercuts at the end of the round managed to stay on my feet but was not quite with it, and realy disoriantated.
for the week after the fight i was in alot of pain with my ribs and could'nt eat properly as i couldnt fully close my jaw.i found this realy damaged my confidense and i found it hard to get back into training after.