Firstly congrats on the finish on your model. Unless the US spec is different to the UK spec you have done a great recovering job. Secondly I converted one of these a few years ago and used a hyperion 3019/10 with a bolly clubman 9.5*6 prop. and 10 gp 2200 Nimh's. This motor is happy with props up to 11*7 on 3s lipo's and will run at 50 amps with no problems. I wrote mine off flying on a misty morning when I got disorientated. Any motor that is about 1000revs/volt and will handle 40a to 50a comfortably will be fine. I seldom use gearboxes nowadays with the many cheap outrunners that are available. With the correct choice of motor/cells/prop you should be able to get standard .40 performance. They are a great sport model. Good luck with your conversion.
Chris.