someone else may chime in with gearing options for you - i'm not one to recommend such things -lol- If you go to the steel spur/pinion combo, make sure you are running hardened pinions...

Also with that 3speed, adjust the points to shift far later than a nitro, as with my LST, brushless rips through the gears much quicker and with a bit more brutality to it - and watch for the big 'CLUNK' as it grabs hold of the next gear -lol-