Flame travel is not as bad as it would apear simply looking at the piston because the flame starts in the very center directly above the piston, not on the very edge of the chamber like a 906 head, a big dome in the 906 head will block the far side of the chamber from a good flame front, not so much in a hemi though.

I am not causing global warming, I am just trying to hold off a impending Ice Age!