I know it is a long shot, but I'll give it a try. Here are some links to posts about this block.
Mysterious 4.1 block - TurboBuicks.com
http://www.turbobuick.com/forums/general-turbo-buick-tech/241074-anyone-know-block.html
Mysterious 4.1 block - TurboBuicks.com
http://www.turbobuick.com/forums/general-turbo-buick-tech/241074-anyone-know-block.html