I ran that TC between my 408 (458hp 503 tq) and built 727 (8 3/4 3.55). It was just fine on the street. No problems or concerns whatsoever. The car was a riot to drive.
I would recommend it, if it's appropriate for your setup - you haven"t provided any details on your Dart.
I also ran a B&M Supercooler to keep the Tranny temps in line. A smaller tube and fin piece was useless.
