I have a fordomatic off a lincoln y-block and a guy that is interested in buying it for an 8ba flathead. I know the torque converter and bellhousing is different, otherwise will it fit?

What year Lincoln? ~AS far as I know Lincoln did not use Ford-O-Matic.

it's on a '56 368, or atleast that's what ive been told. I havent ran the numbers personally. The transmission looks like a fordomatic, it has the same castings in the main case. I havent scraped the grease off the tag to see what it says yet

That trans is the large case FOM, but it will still bolt to a flathead FOM bellhousing.  The case is slightly longer than the flathead unit, and the rear yoke is probably bigger.  I don't think the flathead converter will fit because of different input shaft sizes/splines.  Swapping the input shafts and front pumps will make it fit, but that is a complete teardown of both transmissions.

John - "The Hoosier Hurricane"