The .533 may hit the pistons if they don't have valve reliefs but a .509 will fit with steel shims Must be the extra duration.

I know of a similar combo but with a 727, J converter and a .509 that would run 7.40's@95-96 in a Dart.

It ran really well for a basic combo, 383 with replacement TRW's set .015 out of the hole, stock 906's w/2.08's, MP .509, TM6, 4779 holley, CPPA headers & 3" exhaust. It didn't need a ton of RPM to work either, footbrake it to 4k, shift at 6,200 and run it out the back.