I believe there are "low stall" and "high stall" 10.75" converters. The main way to tell is the refill capacity when changing the atf, by observation, without taking the cover off and looking/measuring. My research revealed that a reman 383/335 (Road Runner) 383 converter and the Slant Six 727 were the same part number. The more power in front of the converter, the higher the stall speed. Just as the stock torque converter for a Chevy V-6 was used behind the 350 4bbls in the later-70s Z/28 cars . . . for a higher stall speed.
One of the hallmarks of the Chrysler TorqueFlite was always the tightness of the off-idle response, which relates to the torque converter stall speed. But it also could relate to "the creep at idle, with the foot brake off", too. This was addressed in about the '65 model year, but CAR LIFE tested it on a Belvedere 383-4 road test, as the car went through the 1/4 drag strip traps at about 8mph. One reason my relatives bought a new '63 Polara 318 was that their friends had told them that when they went into the mountains in New Mexico (for the horse races and such), that with a Chrysler TorqueFlite, you put it in "2" and didn't need to use the brakes nearly as much, due to the "positive engine braking" from the TorqueFlite (and Chrysler's torque converter design). So, that tighter torque converter on the Chryslers also has its benefits.
On our then-newer '66 Newport 383 2bbl, I didn't feel it was sluggish off-line at all. It would lay rubber as long as there was "pump shot" in the Stromberg WWC 2bbl. That was with the standard 2.76 rear axle ratio. Loved that it would cruise all day long at 75-90mph and get over 15mpg doing it. And right at 20mpg at the later-mandated 55mph speed limits.
By comparison, my '70 Monaco 383 N, with the smaller converter, didn't seem to have nearly as tight of lower rpm throttle response until the car got to 62mph, then each "rch" of throttle movement resulted in the speedometer needle moving. Lower than that, it felt a little soggy. That is with the standard 3.23 rear axle ratio.
When the compression ratio dropped in '72, then off-idle responsiveness dropped a bit, by observation. I tried to make our '72 Newport 400 operate as good as the '66 did, but just quite didn't get there. But it was still pretty good, to me.
But then, too, you have to remember that the cars are over 4000lbs with "highway gears", for the 2bbls. Laying rubber wasn't really in their operational dynamics, but great highway cruising WAS. Personally, I'd like that tradeoff myself, more than getting from one red light to another sooner, with a longer wait time at the light before it turns green again.
The way I got my cars to operate better and "more fun for them" was to put a tad bit more preload into the kickdown linkage, from the OEM stock adjustment. NOT enough to cause any problems, but just enough to raise the part-throttle shift points so that when the upshifts were made, the engine rpm was a bit higher for less converter slippage. On the '66, I learned to do manual 3-2 downshifts at part throttle that helped greatly on freeway merges. Mimicking the later OEM part-throttle downshift situation.
Chrysler, by observation, set their linkage adjustments for early upshifts. On the '66, adding two more turns of pre-load did the trick, from the OEM adjustment. At min throttle accel, it would get into high gear at about 28mph. In "fast traffic", didn't need to manually shift just to stay up with traffic, as a result. On the '70 Monaco with 3.23/H78-15, I got it to 2-3 at 25mph. It worked better, too. The '72 Newport 400 2bbl (2.76/H78-15) would upshift at about 25mph, with any acceleration past that "being on the converter", rather than in 2nd gear with a more locked-up converter, generating better throttle response and feel, with less converter slippage (on the earlier non-clutch-lockup converters).
On my '80 Newport, with the adjustments being under the car, I used a thin, black wire tie at the rear of the slot in the kickdown linkage at the carb. Just enough to do the trick. Just looped it over the bottom of the slot, at the rear of the slot.
These tweaks won't affect WOT upshift speeds, which are governor-controlled, just the part-throttle upshifts. And they are TWEAKS, just as putting in an additional 2.5 degrees BTDC into the base timing adjustment would be. Tweaks that help the car operate better and enjoy itself MORE, that have not caused any operational issues at all.
Now that I know about how the wire tie addition helped, no need to make the physical linkage adjustment changes, just add the wire tie to the bottom of the rear of the slot, where the throttle pin will contact it. Easy to undo, too, if desired. But I never went back.
Key thing is to know your vehicular equipment and LEARN what makes it work the best. You'll know when it feels happier doing what it does. When you get to that point, everybody smiles.
Enjoy!
CBODY67