I would say that your 7 would get you started. I know a lot of people that are into the competitive scene recommend that people go to some shoots and talk to the guys there. Get a feel for what they use, what goes on and what you might need. I'm sure that you will find almost all of the guys will be friendly and willing to help and share information to get you started.
I wouldn't worry about spending a lot of money on a wildcat or custom gun right now. You don't really know what you are going to get into or what you'll need. Check them out, see what everyone else shoots, talk to the guys and go from there.