I just noticed this posting today on Seattle Craigslist under auto parts. It states for sale is a 1969 Z28 engine block. There is no partial vin on the add, but there is this info:
block casting no. 3970010
casting date J99
pad stamp V1022DZ
seller phone no. 1-206-762-7691
seller E-mail firstname.lastname@example.org
I think the add stated the block was machined and race ready, so you probably know where this is going, but, you never know?