Is this serious? With that information, we're gonna have more questions for you than you have for us.

You need a track wheel. Why are you looking at a wheel with a 7 speed cassette? And what do you mean by converted frame? Is it just a frame? What is it converted to? Does it already have a fixed wheel on it? As to what else you need--according to what you said, you'll need everything but a frame/front wheel it seems.