When I first got my Turbo swap on my 2.6 Monti done I was always frustrated in that every time I would squeeze on the throttle the engine would rev up to 3K or more. When just loafing along this is frustrating. Once I upped the control pressure and got a low rpm lockup converter I could make good use of the added torque the engine provided. Now that was a pre lockup transmission but I am curious if what you are experiencing is an early unlock of the TC allowing the revs to flash to where the NA engine needs to be to make torque but is now above where your engine starts to be strong.
I have not looked into the early lockup transmissions but my approach would be to,
1) Find the control circuit for the lockup and delay the unlock.
2) See what other Torque converters have a lower stall speed to hold the low end torque you now have. Mine came from a V6 Toyota.
3) Consider a change in the valvebody to the control pressure valve. I machined a new one that ramped the pressure up much more quickly than the original. If you can get the valve or even a valve body I can make some up.

Once you can get the transmission to hold the torque better than you can get a better long term feel of the powercurve.