I used to live 2 miles from Norton AFB and one year they had a big dog and pony show with a bunch of P-51s doing a "scramble". As I recall they were all natural aluminum.
My first thought was "Conquistador del Cielo" which was the GeeBee QED in an earlier incarnation. The apparent R22 under the wingt could be a racing number. Only problem is this machine appears to have a 3 bladed prop.