Might suggest to him to check the date code on the block. Several years ago when I was still in So CA I got a fair amount of money for a 1970 block that I had planned to use for a dirt track engine I was building.A friend ( a retired boat shop owner) has an early 350 Chevy four-bolt main bare block (standard bore) and some related parts for sale. Located in Upland, Calif. He also has some 454 BBC parts available.
Call Joe at (626) 664-9224 for information.