I'd put some serious thought into the project mate. I know a couple of blokes who are running in Sports Compact and they have serious weight issues in their GTi's, meaning they have to run ballast to reach minimum weight.
Makes building an MB drag car a bit of an issue - especially when they have such a shocking chassis design.
But best of luck with it if you do decide to go ahead. If there's any help you need just post up on this forum, I'm sure someone will have an answer.
Also if you have any pics of the project as it comes along let me know, I'll be happy to put them up.