My current one is a Hemi pattern head. The last one was a Wedge. Supposedly the Hemi stuff flows a tad better but I have not found that to be the anymore than a nominal difference. We care more about port shape, cross section and runner CC than a flow number. At least with where the heads were ported the numbers are pretty much he same. I would think block availability is ALWAYS a consideration. Last one was a Wedge head because that was the block that was available. This one is on a KB hemi block, likely the last one from the original KB.