if you post a want ad in the classifieds here
, I am sure someone will have one laying around. The 360 crank is pretty ubiquitous. Or if you post a want ad over at theamcforum.com I am sure they will help you out, too. There are awesome folks on that forum and they are ridiculously helpful. No way I could have finished my engine build without them.
I see you have a wanted ad for the whole engine over there already. That's good! Also, SC/397 usually has a few cores laying around. If I ever need another AMC V8, that would be my first contact. BUT he is about to retire so gettem while he's hot (he may not be taking any more builds on but I am sure he would be happy to sell some inventory off, like a crank or 360 core).
79 Cherokee Chief (passed CA smog check Sept 2020)
(Cherokee Build Thread)
11 Nissan Pathfinder Silver Edition 4x4
09 Mazdaspeed3 Grand Touring