Ace = fine in a truggy, plus gear sets are cheap.
Futaba do a 351BLS with 15.6kg torque if you want something a bit more meaty - the 452 I'd run in a buggy or a truggy but if you're buying new of the 2 Futaba options I'd grab a 351.
You don't really want a high voltage servo with a li-fe pack - they're intended for unregulated li-po so you won't see the benefit
__________________
|