1st of what esc dose it have as you will have to make sure the esc and motor will match on turns......as for the nimh i would go for the vapextech 5000mah or maybe switch to brushless and lipo as you will gain alot more ie runtimes etc
i have some brushed motors but 19t's for sale and a brushed waterproof esc but has no revers as its a racing esc but that will take any thing upto a 5t limit and 2s lipo on brushed..
cheers K