check out:
http://www.newenglandsharks.com/shark.htm
I ran into the guy who won either last year or the year before...he did so on the smallest boat in the tourn. (24') I think he said he got a big mako. I don't know how big the tourn is.
I know Montauk has a big one. You may want to look into that too. I was there one year when it was being held...some monster fish were brought in.
suggestion: Never bring a mako in the boat unless you're *sure* its dead!