Ok I can see the pic now.
this pic shows the nude WRC body shell, so I don't really see what you aim to do in terms of modifications as the rally cars plastic kits made by brands are of course already modified compared to street cars to be accurate as much as possible to the racing versions.
I probably have misunderstood something in your question but I don't see what to say, if you intend to build a rally car just buy a rally car kit and you wouldn't have to modificate anything on the body, being able to concentrate on details.
I may have pics from these years WRC but need to take a look at my books, haven't much on the computer.