A couple of things.... First off, I watched a guy use oven cleaner on the painted name on his fiberglass boat. It was messy and a lot of work, however, work it did!!! I would try the fiberglass paint remover first. Also for the new name, I would use vinel stick ons made by a sign shop that does not necessarly deal with boat names. My boat name with a contrasting boarder, my hailing port in fancy letters and my bow numbers all cost under $60. They have been on for two years and still look great. If they fall of tommarow, I will consider it money well spent and do the same thing all over again.
Good Luck and happy sailing