Looking for a steel narrow journal even fire crank...3.500 -3.550" Stroke. I know it's a long shot but I also know there is some odd ball buick stuff out there. Let me know if you have anything along these lines.
Check with Byrant they may have one in stock. If I recall when I called them last year had a new 3.500 on the shelf that has been sitting around. Not cheap though. Good luck.