P-51 may try for 4 1/2 to 4 3/4 on CG mine flew great, but I could really notice it go tail heavy as the fuel tank got low at 4 7/8 CG. Comming in on landing with no fuel and 15 mph winds the nose really wants to stay high. If using a 46 fx and going buy the book you will need 2 oz of lead way out on the cheeks, only one problem with that was when I needed to adjust my low speed needle I had to drill thru the lead. Since Hangar 9 did not include a spinner you might want to use one of the brass heavy hub spinners, but out that far on the nose you will only need around an ounce IMO. If you use a plastic spinner go with a DU-BRO 2 1/2 yellow, its the closest color match to the covering. I consider myself still a newbe to R/C and this is my first low wing plane, with some expo on transmitter this plane was very easy for me to both fly and build. It floats in as good as my trainer does and with time and more surface throws I will learn some 3D as well.