Hey Sam,
I apologize for not checking back on this thread sooner. Bummer to hear about the crashed plane. I wish you had some video of the launches and crashes so we/I could see whats going on and possibly give you some tips.
It's really cool you met a WWII pilot and made a new RC friend. I highly recommend checking out the RC club he suggested. A place like that should be full of people with suggestions and advice and probably a couple people willing to help you get in the air a little more successfully.
As far as the P-51 build kit goes, the answer is yes, your power system would work fine in that plane. However I have to say if your having trouble with the Versa then I would NOT recommend building and trying to fly the P-51 SBK. I highly recommend taking a step back and trying something a little bit easier to fly that will accept your current power system like maybe the
Old Fogey or the
Simple Storch with my first pick going to the Old Fogey. These high wing planes are generally a little more docile and have good self righting characteristics. They also both have wheels so take-offs should be a bit easier.
Remember, if your having trouble with something, get video of everything from launch to crash. That will help people like myself to give you better advice on whats going wrong.
I hope this advice helps and best of luck!
-Mike