If you use 1/8 diffs (so no e-revo style diffs) I would look for 30k rear and 50k front. That's what I run on my Savage and MERV and it's good for bashing purposes.
Mugen MBX6Te RCM + Mugen MBX6e RCM + Savage Flux XL FLM + MERV all with Spectrum DX3S || WTS&WTB