I'd have to think that if you told folks what you were adapting th Y block too someone could come up with an exact solution although the three mentioned above are go to adapter sources. Bendtsen's web page http://www.transmissionadapters.com/ford_y_block.htm Wilcap link http://www.wilcap.com/webdoc8.html
If you are looking to adapt an automatic, then just go with an MX or FMX automatic that will fit right up to the 272/292/312. It has removable bell housing, so you can get the bell off a Furdomatic if need be.
I would research which automatic you want then who sells the best adapter kit for that application. Not all of them are equal. There is pros and cons to each. My preferred od auto trans is a 200r (brand be damned) and one of the listed companies make the best one. Good luck