The slant edge faces the tranny on mine also. What you really need to watch out for is how the torque converter bolts to the flexplate.
Check the clearance between the torque converter bolt "pads" and the mounting surface on the flexplate. You have to make sure the torque converter is engaged/indexed into the tranny correctly prior to this check. Then you mount the tranny to the engine. Do not connect the torque converter to the flexplate, but instead measure the distance. Make sure this is up to the factory specs. If the gap is to wide then the torque converter will be pulled to far out of the input shaft area (you will need to shim to get the correct gap). If the gap is to small, or non-existant the torque converter is not engaged correctly with the tranny.
The gap specs for my Pontiac 350 and 200-4R are between 3/16"-1/4" gap. I'm not sure if this is the same for your 400/400 combo.
