The B-25 strafers flew a lot of missions in WWII PTO at less than 50 feet, so I'd go there. Reliable with range, power, lift & room for new weapons as needed.
Hope this helps for future endeavors:
http://www.enginehistory.org/References/ModDesig/jpg/moddesig.shtml
If you got to the engine entries, you'll find the aircraft that the engine models were used in; see attached for early Allisons as an example.