I have done a few boxing matches now and also have three booked in for October,
The senior referees do not allow flash with any ABA boxing during the fight. However, in between rounds they let you use flash.
They dont like you walking around the ring during the rounds, I was told to pick a corner and stick to it...That basically left me with either of the neutral corners during the action, but I also had freedom to move to the working corners in between rounds.
Another issue I found was that if you are in the same place all the time the punters dont take too kindly to you poopping up and down at the time of the big hits..lol
It pays to find out who the senior referee is and pay respect to this guy as he ultimately owns the event.
I have used three different lenses with varying degrees of success.
50mm f/1.2 , 85mm f/1.2 and a 135mm f/2.0, all three have their own plusses and negatives.
If you have the space and access to create a 4ft platform, this will get you above the ropes. We did this at the British junior ABA's at the Metrodome in Barnsley with some fantastic results. We had a lot of space and also there were angles where we were not obstructing any of the paying customers view.
I found when I was shooting that I was like the defending boxer,,,watching the attacker for the big hit...instead of defending it, I wanted to shoot it.
Another point to make is the DOF ...if its too shallow you will only get one of the boxers in focus....Pray the lighting is fair to good. Expect only a 35-55% usable images....
The audience is also a great area for action images...The referees and timekeepers all offer great oportunities for images too...
Good luck
Tug