Congrats and Welcome!
We have a couple folks here that have Man-O-War's and have done some work on them,, hopefully they will check in soon for you!!
Not sure but I believe the serial # and the HIN are the same...
If that were my boat I would I would Dremel out the cracks, sand it all down, fill the holes with epoxy and lay up some fiberglass to smooth it all out and add strength, redrill the holes, paint the whole transom, go sailing
Don Casey has a good book on "Sailboat Hull and Deck Repair" that's good for all things fiberglass... check out this link:
http://www.boatus.com/boattech/howto_lib.htm
Billy