If you haven't seen this already, you may find it useful for information regarding the Schumacher Menace:
http://www.rcuniverse.com/magazine/a...article_id=414
Also, if you don't mind the truck being 2WD, look into the Traxxas Jato 3.3. That will probably be a little squirrely as far as stock performance in grass but it will achieve your speed demands without a doubt.