The 4-7,2-3 switch (18726543) firing order is actually the same as the small block Fords if you look at the way Ford assigns their cylinder numbers.
From Dave Reher..."The order that we call the "4-7 switch" (1-8-7-3-6-5-4-2) has produced 5-8 more horsepower in our pro stock engines and was a well kept secret by racing teams for years."