You can play with it in the speed calculator to check for sure, but I think you may be able to use stock gearing and just go smaller spur/larger pinion to make up for it. The brushless motors have a little more capability than nitro.
Edit:
Here it is set up with a 1512 1.5d running 4s lipo and the Revo wide ration second gear. You could also sub the 50mm 3300 kv medusa in there as well.
| Differential Ratio: | 2.8461538461538463 |
| Transmission Ratio: | 2.111111111111111 |
| Other Ratio: | 1 |
| Spur Tooth Count: | 38 |
| Pinion Tooth Count: | 16 |
| Total Voltage: | 14.8 |
| Motor KV: | 3300 |
| Tire Diameter (inches): | 4.37 |
| Tire Ballooning (inches): | .5 |
| Motor Current Draw: | 0 |
| Motor coil Ω: | 0 |
| Spur/Pinion Ratio: | 2.38 : 1 |
| Total Ratio: | 14.2703 : 1 |
| Tire Circumference (inches): | 16.87 inches (428.51 mm) |
| Total Motor Speed: | 48840 RPM |
| Vehicle Speed: | 54.68 mph (87.83 km/h) |
| Estimated Adjusted Speed: | 51 mph (81 km/h) - 7% loss |
| Effective KV Value: | 3300 |
| KT constant: | 0.41 oz-in/A |
| Motor Torque: | Amperage not specified... |
| Final Torque: | Amperage not specified... |
| Final Power: | Amperage not specified... |