Just remember...the coverter will change stall speeds when a change occurs in the torque curve. Not just the total amount of torque, but also the shape of the curve.
What I'm getting at is let's say you get the converter right for a nice, streetable 360 and it has an effective stall speed of 3k just for discussions sake.
Now, you build a nice 440 and use the same coverter. Not only did you more than likely increase torque, you will be making more torque at a lower RPM than with the 360. That right there will INCREASE the effective stall speed of the converter.
The corallary is the same. A converter that has an effective stall of say 3k on a 440 will tighten up if you put it behind a 360.
How much the stall changes is based on torque/torque curve, gear ratio, car weight and...
I'm sure you know all this but it's worth typing it out.
