I would look for a stock 11.0 inch Street Hemi or one out of a 383 or 440 magnum so it will work with the 1966 and later 727 trannys, there not real loose or real tight either. The big stroker motor should make it act looser than if it was behind a stock magnum motor
One of the old Mopar drag race engineers said at one of their seminars back before 1980 that the loosest stock 11 inch converter Mopar made for production vehicles was for the 1970/71 383 two barrel motors in station wagons
I have ran a custom built 8 inch Turbo Action race hemi converter in my old pump gas street Duster with a bunch of different gear ratio, 3:73,3;91,4:10 and 4:30 in the 8 3/4 in that car, it loved that converter and so did I It was way better on the street than the custom built ten inch converter I had built for that 511 C.I. pump gas motor
Torque converters and brain surgeons are two thing you don't want to skimp on AKA aside, buy a really good one
IHTHs