There are tons of steering servos out there that all fit the bill. Depends on your budget and what you intend to do (play or race), here are a couple of alternatives that would all work well:
budget solution: Hitec 645
Medium priced: Hitec 5945 or 5645,
The 90 USD+ solution: JR 9450, Ko-Propo 2143
These are just a couple of the top of my head...
As for throttle servos: Torque is better than speed, look for a servo with a torque rating of 60+ ounces. If you run a digital servo on the throttle, be aware that they tend to burn out if you dial in drag brake in your set-up. To avoid this, stay with analog servos for throttle/brakes. (This is only a concern if you run dragbrakes). Speeds of 0.15s and better @ 6 volts is more than adequate.
Good luck !