if you're taking the servo off your 1/8th buggy steering, replacing it with anything between 12kg-18kg with 0.13-0.15s would be good enough.

if you're taking the servo off your 1/8th throttle, replacing it with anything between 12kg-20kg(or higher depending on your brake abuse) 0.7-0.13s would be good enough.

I know it's odd that the higher torque is for throttle but lately i've seen and heard of many throttle servos dying before the steering servos.

From the other thread:
the preference so far where i am are:
Hitec TGs (I have not tried that but they offer the 7940 which is great, 13kg with 0.07s)
Futaba BLS (I have the BLS-452 for my steering but would have taken BLS-351 or BLS-352, both out of stock here, they are really smooth, quiet and servo horns fits perfectly)
Savox S-1256-S1258 (I have the S-1258, a bit loud and rough but response is fantastic)