The key word is "good". They are still out there and some restorers have them available, but most I have seen are cracked, usually between a valve seat and a cyllinder. I offer below the Internet address of the source of the "French Flathead" which looks very interesting but expensive. Keep in touch if you get a good block because I have a 4" stroke '49-'51 Merc crank with used rods and pistons with flywheel.

http://www.reds-headers.com/html/ffh.htm

Don Shillady
Retired Scientist/teen rodder