35 mph WOT power loss

For the TF-II
A&A can send you pre-machined sleeves and weights to set the upshift rpm to whatever rpm you choose, and then you will have a small window of adjustment availability to fine-tune it.
Adjusting (fine-tuning) is done by the KD mechanism, it's all external.
The only adjusting you can do "on the VB" is to; line pressure, and the TF2 kit tells you where to set it. When you set the "line-pressure" to their specs with their parts, it is usually a one-time deal .

Automatics are pretty simple; Here's a quick overview;
The faster the engine spins, the more line-pressure is produced..
The faster you drive, the more governor pressure is produced.
The further your throttle is opened, the higher the line-pressure is commanded to be.
Line pressure is your main controller.
The governor comes along and fights the line pressure to command a shift.
If you have an argument with the governor, and want the rpm to be higher prior to the shift, your main way of doing that is tell the governor to back off, using "Throttle pressure", aka KD pressure, the mechanism connecting your carb to your KD lever.

The line pressure is increased by the throttle pressure to fight the governor pressure, into delaying the shift to a new higher roadspeed..
That's all there is to it.

The 600DP is more than adequate for your combo in the city. If Rusty offers it to you complete for a good price, I'd say jump on it.