On the GVOD sit there is a section of Q@A
This one was quite informative even made me go Hmmmmm
Can I run a high stall converter in overdrive with a 3.42 axle?
Here is the link
Gear Vendors under/overdrive, Frequently asked questions.
Here is just a snippet of the article......
"When his converter was made it was set up to stall at 3500 with 400hp. However if you put 600hp to it, it would stall at something like 4500. Conversely if you only put 125hp to it (as when you are just cruising at 75mph not accelerating) then the stall is way down at 2,000 rpm. So his stall with a 3500 converter is not 3500 at cruise because he is not making 400hp"