More than the dimensions look at the weight that you will be adding also.
I'm not saying it wont work I'm just saying facture the weight in also.
In a vehicle this small weight has a bit more impact on overall vehicle handling.
I'm still waiting to read the reports of 2 celled LI-PO's being used and if the stock electronics can handle them.I suppose someone could make a failsafe for it.Either a simple fuse or a voltage limiting circuit but what is the safe threshold of the stock receiver & ESC & servo units?
Or you could just use a 1 celled high MAH LI-PO battery and have massive runtime but with a reduced voltage/speed.But it would most likely be lighter than stock batteries.
http://www.bphobbies.com/view.asp?id=A0320104
http://www.bphobbies.com/view.asp?id=A2416227