All this talk about locking the front diff spurred me to chime in. You guys want a similar setup to what the 1/10 TC cars run. Diff in the rear and a spool up front. This will give you 4 wheel brakes and will allow the car to rotate. the trick is finding a diff that will fit. Serpent used to make some really sweet rear diffs and I'm sure there were others back in the 2wd 1/8th days. Just need to do your homework.
http://www.serpent.com/product/808390/
There is a 50 tooth pulley option. I have one of these and they are very trick.
I've attached some pics of my projects.