chevy, I'm not a diesel guy so take this for what it's worth... as I understand diesel conversions they give more torque and swing a larger prop than on glow... I'm guessing your putting out about the power of a 50ish 4 stroke motor... if this is correct then you'll need to stay close to 4 lb to get what you want. Most any of the profiles will get you close to this weight and perform well... another choice would be this plane http://www.hobbypeople.net/gallery/123740.asp what ever you chose try and keep it close to 4lb AUW.

John