Hey John
We are talking Pheonix right ?..
If so I did my first one at 4 inches and found it very tailheavy in flight.. Looked kind of like a porpoise in flight . I changed the CG to 3 1/2 which seemd to be a much better starting point on both of mine...
With both of mine (Saito .56 and Saito .72) I had to mount the battery about 2/3 of the way back in the fusalage to come out right.. To balance I finish the plane up minus the battery, put the plane on my CG stand then slide the battery pack down the fusalage until the balance is where I want it.. Then cut the bottom of the fusalage open at that point and mount the pack ..
I am waiting anxiously for your flight report .. I think this one flys a lot better...
I also added some differential to the ailerons on mine... Helps a lot doing those slow speed turns