Personally, I quite like the specs of the Great Planes Rimfire 46 for these 40 sized classics. 42-60-800 makes for a motor that requires short standoffs and the 800 KV means that one can get an 11" or even 10" prop up to rpm and produce ~900W of power on 5s at under 50A.

A 4000 mAh 5s pack gives 5 min at WOT or ~10 min managing that throttle.

David