Hello Mark,
If you search for French Flathead on this forum, you will find quite
a few references to this engine. Brian Kitcher in the U.K. first fitted a Ford diesel, and then a French Flathead in his F60S LAAT. No details about the conversion, though I have heard several people did this conversion.
Maybe this webpage is of help, as it "outlines the necessary modifications and changes when installing the French flathead in an otherwise unmodified Ford V8 vehicle":
http://www.btc-bci.com/~billben/french.htm
Here's hoping you go ahead with the conversion and document it here for the membership to learn from.
Hanno