Convert desktop .Net application to ASP.NET

There is an existing desktop application available. The source code of this will be provided to the chosen freelancer The job of the freelancer would be to convert this code to a web based code. It requires primarily the core logic to reside in classes which can be used in the web application (this is basically reusable from the existing application), and some controller/model code to be evolved. I'm looking for a good UI as well. So, while I'm comfortable giving the work out to a developer who can follow proper MVC methodology and can also work on the UI, it is not important as long as they can work with any other designer I bring to the project to get the UI part complete