The above post mentioning the Pontiac SD reminded me of a 2.5 litre hydro I saw about 20 years ago with an aluminum, crossflow, SD head on a Chevy 11 block. It looked like it belonged on it. No big gobs of goobers sealing up the pushrod side.
The heads would be hard to find now, but I'd bet they are still out there. Also, I just downloaded a picture of a 181 Longblock showing an 8 port head.
Although I'm certain that an LS style head would have superior airflow to a 20 year old SD head, the SD would certainly flow better than what we have, and should be a bolt on. Pontiac also sold an upgraded, over the counter 8 port with the casting number 347056 in iron.
