[nota]

Originally Posted by JavaBrewer

I agree with Steve. The SD 455 somehow got under the radar.

Edit adding YT video

https://www.youtube.com/watch?v=C4tV426_Ih8

few even know of the 71 only ho 455 round ports and hi-compression
in the t/a only
I had the block 4 bolt in my 68 GTO but never found the heads