Depending on the engine the main difference between a heli and aircraft engine is the head. Some heli engines also have a midrange needle as do some ducted fan engines.
I have seen helicopters that were designed to be able to use an aircraft engine. These helis also had a cooling fan and shroud to direct air over the engines head.
Putting a non heli engine in a heli designed for heli-engines will more than likely lead to overheating-unless you change the engine's head. Then I guess it would be a heli-engine!