Well I kind of have a history of making player types too high poly or not blocky enough for BL, but I could try. How did you want him to look exactly?
The hips on the tank in L4D2 are normal sized. If you take the default minifig, bloat the size of its chest, get rid of its neck, and replace the hands with oversized (yet detached) globs of muscle and fist, it should look nice.