P-51 will be a major handful. Nitro planes are much faster than electric and P-51's are in the higher end of that range (not counting jets). PLEASE get a high wing trainer, they do make 60 size trainers and it is true that they are easier to see and more stable as a rule than the smaller ones. From there you can move up to a low wing plane or two and finally to the P-51. Most military scale planes can be tricky to fly. Since you have electric experience you will advance quickly but not instantly. the landing approaches will be much different and faster.
Good luck.