Sorry, but as CD it's my discretion and I'm not alone, there are quiet a few who won't sign you off unless it's a turbine aircraft, and there are just as many who don't mind letting you use a prop plane.
if you read the qualification portion of the application it states as follows:
Objective: The purpose of the flight test for the turbine applicant to demonstrate their skills, knowledge, and understanding of how to safely operate and fly a turbine model aircraft..
i don't see that happening with a prop job...........but it's my opinion and other CD's have their own discretion on it.