Too much to type out on a nexus 7. Grab a coffee and watch:
www.youtube.com/watch?v=uXgSttKLsHs
Lockup and stall speed are two very different things.
At the risknof oversimplifing it, you chose a higher stall speed to allow an engine to produce more power before applying it to the transmission/drive wheels.
Great for the dragstrip, sucks @$$ in a daily driver.
Friend of mine once had a 71 Z28. Had himself convinced he wanted a 3500 converter. I tried to tell him why it wasn't a good idea. Didn't listen but went with a 3000 instead. Worked great on weekend stoplight contests (well, would have if he could drive worth a hill of beans). No one would get in the damned thing with him the rest of the week. Total dog in daily driving at best, way too abusive to be in at worse.
Women hated the damned thing. They enjoyed my Mustang Mach I Cleveland/C6 with the OEM converter much more. I could pretty much spank him at the stoplights when I wanted to also.
Not the effect he was after......