will a ford-o-matic off a yblock bolt onto a flathead??

[54mainlinetim]

Hey guys!
I have a ford-o-matic that was mated to a yblock that i am trying to sell on craigslist, A guy called me up asking if it would mount up to a flat head? I told him I know that earlier fords then 54 had flatheads and fordomatics but wasnt sure if a fordomatic off a yblock would work or not on a flathead and told him i would ask you guys and let him know....even tho im selling it cheap I just didnt want to sell it to him and it not work....sorry if its a dumb question im just not hip on flatheads..thanks for any insight