I've thought about the same kind of thing. Not just engine sounds. Doesn't a WWI plane during a low pass across the field just cry out for the "taka-taka-taka" of a vintage machine gun?

I saw a "Spirit of St. Louis" at the Rhinebeck R/C weekend last year and it had a speaker deal in it. When it flew past the flight line you could hear Jimmy Stewart shouting down, "Which way to Ireland?" Very cool. Only trouble was that the plane had to idle down and the crowd had to be pretty quiet to hear it well. Don't know how it was done though.