isnt the extended block the bellhousing? they have a lower section that bolts on to it and the trans bolts to "bellhousing" so if you had the lower section you should be able to have a flat plate made that you could mout the trans to, possibly?that is how the factory did it i am sure they had manual trans on those motors, you just might need to make the plate fit the later trans bolt pattern and make sure the imput shaft went in far enough, the one on that link is just like the factory except drilled for a chevy you could do the same thing relativly easy with the correct measurements and machine work, and a flat plate of alumuinum