It will be lot simpler to get the brushless. 5700 KV or less, with lipo you will have wheelies on demand from half throttle. Other than a good dusting off, and oiling the bearings no maintenance will be needed.
Take it from someone who owns a Pede and have for over 3 years now. I have used 10t on up to 21t and Frankensteined alot of brushed motors in-between. 15t in a pede with seven cell NIMH is just going to run supper hot burn your brush's up supper fast and destroy the motors comm. IMO the best turn Brushed motors for a Pede is 17td and up, and if not geared correctly you will get heat issues out of the 17t.
Go brushless, I suggest MM, Sidewinder, or MMP. So you will be able to tune the brushless system to the application. You can save profiles that you like name them (Dirt, Street, Track, Bash) and with a click it will run to your liking for the situation. Go with the brushless you won't regret it.