I was considering the swap when I got the custom roller for my 406. After talking with Earl, Harold and several others it was decided that it was a waste of my money that could be better used somewhere else in the build.
Earl even spoke of making the swap to the LS1 firing order on a build that didn't find any more power.
From what I gathered, on an "ALL OUT" build (especially heavy nitrous) the 4-7 swap might get you better cylinder-to-cylinder fuel distribution, but nothing 99% of the builds out there will ever get into.
I did dyno testing a few years back on my 414" with 2 Lunati's--it wasn't worth much, but since I got a lot of free stuff..........
Warren Johnson will tell you the dyno will show nothing, but the car will go down the track a little faster...?? It seems to be ever so slightly smoother, but if it costs more, don't bother.