[Overdriven]

Lets tackle the battery issue first. The Rc-monster battery trays for the above vehicles will hold just about any length battery, ditto for the Losi conversion tray. The Associated conversion is limited to the standard ROAR approved hardcase battery length. I forget the dimensions of those but they are shorter than other availible Lipos.

Buggy. I've had an RC8e, and a Losi 8ight 1.0. I found both to be about the same durability wise, but I like the 8ight just a little better handling wise. Wish I still had it, but I moved away from buggies and then came back to them, but more cheaply this time with an LX1e.

Which I run with a cc1518 (1800kv) on 5s. Currently geared for 50mph (with no tire ballooning in the speed calc) and it runs cool, even in grass. I had a CC blower around so I put it on, but there's no holes in the body (which fits pretty tight so not much airflow) and even in grass my temps stay under 110 on motor (esc is in 120's) after a 15-20 min run. Some might say its more motor than you need for a race buggy, and it is, but its an awesome bashing motor. It pulls my gearing no problem and shreds the tires at any speed. I'd run it on 4s if I was going to race it.

You might be able to set it up for 65mph on 6s and have the temps stay in check while racing on 4s too. But usually thats not the case and a pinion swap is usually required when changing the cell count that much. A bigger motor like this might not mind, but you're going to have to test it out. If you go with an RCM mount, swapping between your track/bashing pinion and the extreme speed pinion is pretty quick and painless. Anyway, hope this helps a little.