Let's be honest....

You should not need an adapter to use a 727. A small block 727 will bolt right up to the 5.7 hemi. You will need a special flex plate to account for the difference from the crank to the converter.
This is correct! As far as the flexplate goes, there are aftermarket flexplates out there for this swap, but back when I did mine there weren't. I used the flexplate that came on the engine, a 2004 truck engine. I took it to a machine shop and had the welds cut off on a lathe that held the starter ring gear on, and removed the ring gear. The bolt holes for the torque converter are spaced metric, and may be a hair off to the outside if I remember correctly. I believe I had to file a slight bit off the inside of each bolt hole to get the bolts to go in. This doesn't affect the centering of the torque converter, as it registers in the back of the crank.