If you wanted something that would deliver a number of interesting conversations, this script would go from being fairly static and simple to dynamic and complex. It would take a fair bit of work to make it work in a way that I would be happy with. I'm not making any guarantees, in fact I wouldn't consider it as anything at all, but I may work on a few mock ups because I like the idea. If I'm satisfied with the results, I'll let you know and go from there.
If you did want something fairly complex, however, I would probably need to request additional information, especially with regards to the type of conversions you want to have and how topics are determined, how the flow of the conversion would be affected; there's quite a lot of things I'd probably want to know to make this a really good script. It would take a lot of time, however, so I'd consider how long you are willing to wait. By a lot of time, I mean anywhere from weeks to even a few months based on what happens in life.
If you only wanted something static, it would likely take less time to write up but would probably require a lot of time on your part to set it up. Saying that, I have no idea how much setting up a more complex script may require just yet.