Well I hope I can help a little. I have been researching these brushless/LiPO conversions and am going to convert a nitro monster truck soon enough. I have found some great websites and here is one I got from RC Car Driver's electric Revo,
http://www.rc-monster.com/ they put two 2cell 8000mah 7.4v LiPo's in that revo, each pack $110. Plus a gnarly Quark Monster Controller that is about $280 and a feiago motor. There is some crazy over the top systems you can do, but what I think I am going to do is get a novak e-maxx brushless controller, some sort of feiago or "exotic" motor like that, or just the motor the esc comes with. and dual 8000mah LiPO's. Although there are some way better esc's. you can get. I have heard fine designs conversions are crap, and they are INCREDIBLY overpriced, I mean $1350 for a converted LST2. You can do the conversions yourself so much easier, the way I think of it is the only hard part is finding an endbell/pinion gear for the motor to the nitro tranny, and fine designs carries tons of different shaft size gear endbells that will work, get one of those, and start scrambling through your random parts bin and start fabbing some parts. It'll be fun! BTW the brushless Revo ended up doing 48mph and running for about 25 minutes, outstanding power and since it's electric I can just imagine how fast it got to 48! Basically, go on
www.rc-monster.com and try not to go too crazy because they have some over the top stuff there!