I have a Turbo Action "J" converter that was custom built for a completely different combination, totally unrelated to mine (572ci, high compression nitrous A body).
According to Paul at TA it's built as tight as they can possibly make that configuration. It's only around 4500 flash with my wimpy street combination.

Overall I do like it, but I've found the more I load the vehicle down the less I like it.

Back in the days of dragging around two extra wheels and tires, full size steel floor jack, jack stands, couple tool boxes, etc etc etc
(And then hope like hell Blusmbl would show up and help me change the tires), it did feel pretty darn sloppy after an hour and a half on
M59 and 23 commuting to and from Milan in the summer heat. The rest of the time, no complaints. Driving a shorter distance to and from Lapeer and NOT changing tires,
and not hauling tons of extra stuff around, I get along with it much better. Normal cruising without a big payload, it's good.

If anything I'll be adding weight to the car, and 451ci to 572ci is a substantial jump, but I'll try it with the big motor to see if I can get along with it.

Honestly I'd prefer it to be tighter for driving around, and maybe a 572 ci street engine doesn't need all that stall speed, but there's only one way to find out.

Oh, and when I redo the interior I'm putting the 4 speed piece back on the trans tunnel as Chrysler intended.
Because.....well, you never know......The pedals are still there.....
I'll mount an automatic shifter to it but who knows what might happen later?