Trans and converter
The tuning has nothing to do with the stall, just the shift points and rev limiter. It can affect line pressure but that wouldn't change the stall speed, that is all via mechanical parts.
If by "built" for 2400rpm you mean that's the stall speed, than that is a pretty low stall for such a large cam and head package. You can't tell the stall speed unless you have a transbrake and can hold the trans to the stall speed. Even then it's not perfect.
You're probably leaving a lot on the table by having a 2400 stall. I have a 3600 stall and I'm nowhere near the power you're making. Most people with your setup are running 4000-4400 rpm stall for street/strip applications.


