hi, if the Miss America is a 72" wingspan P-51, the 137 is way too far back, my 72" B Model P-51 has a CofG at about 110mm back from the center join of the wings, Move your fuel tank back over the CofG if you can, less likely to nose over with a full tank that way, mine has a DLE 35ra in it, it moves, mine also flies with a little bit of down elevator, 3/8 up travel will be heaps. have heard of people using a further back CofG than I do, but I find my Mustangs are nicer to land with with a slightly forward CofG, originally they came out with 150 something in the book, it was instant flip on take off.
hope this helps,
Oldtimer