One other thing I was going to say is I do not think you will be under powered,but to be on the safe side do not try to power the cap off the ground on takeoff.Make sure you have flying speed and do not climb at a high rate the first few flights until you find out how it is going to do.Again I think you will ok because I have extra 300 with a 71 inch ws and it has a webra speed 120 and flies great.But I think the 16/8 apc would be a better prop for your set up.Good luck.