I haven't ever seen only a complete crankshaft for sale, haven't just seen parts for a crank for sale either. There is a member on here that would know though.
Speedchaser sells lower ends so he's probably the person to reach out to. He also has an eBay store selling completely rebuilt crank cases, and other things as well. He is willing to discount his stuff if you buy through here instead of eBay.
I haven't heard of ftz before, but a quick google search does indicate they are atv
Engine modifiers out of Missouri. Looks like you might have found a former raced odyssey, that's cool!!! The people on this site are super knowledgable and eager to help! Congrats on the new toy, good luck on the rebuild, look forward to seeing your progress.
M