I bought a used Hanger 9 P40 about two years ago from a fellow club member. It has an OS91 4Stoke for power and a really cool Kelough exhaust. I removes the aft servos and moved them to the more usual spot in the center of the plane. I also had severe nose-over problems on take off and landing. They both got much better when I moved the CG aft to 3.5 inches. The plane flys great with much improved ground handling. I have 4 Hanger 9 warbirds and believe that Hanger 9 made a mistake on this plane when they called for a CG of 3 inches.
In the two years that I have had the plane, I have had nothing but problems with the retracts. I do not like the additional weight and complications of air retracts so I have been waiting for a good set of electrics. I have followed an ongoing forum on Wingspan retracts for this plane and have very reluctantly installed them in place of the originals. They are not very powerful and may have excessive slop in them. The plane is ready to fly, just waiting for some good weather.
Whatever you do with this plane, do yourself a favor and move your CG back to 3.5 inches. You will be glad that you did.