Nitro staff can verify my comments , but the 60 size P40 (not the CMP versions ) but the one that has P51 style retracts , was originally designed by the company that marketed under the sportman avaition brand .
I have over 9 P40 so I sould know because I have these planes .
The original design was very easy to fly and can be flown eletric .
When in doubt on the CG , use 25% of the maximum wing cord measured near the fuse .
If you have never build an arf , get yourself a good book avaiable on any web or hobby shop on tricks and techniques .
It will give you tons of pointers on cutting cowls , pushrods exits ect .
Or look up the original VQ P40 build thread , ton of good points on arf assembly that yuo can use .