Especially if you want to race. There is no sense in building a boat that there is no class for. If you motor is an inboard you are looking for a cat hull, Outboards run on tunnels and can be put on monos riggers and cats but they are at a disadvantage to the inboard versions as they have to run with the regular boats of that class. Someone in the club may have a boat for sale and could help you get set up. I do have a cat for sale but it is a 67-80 boat Join a club as you will meet some of the best people around and you will have a lot more fun!!
Brad