I dunno exactly what you are asking but maybe this will help;
If you get the 2>3 working nicely, but
the 1-2 is too early or too late, the only option is to change the 1>2 shiftspring.
This happened to me, with my 318-4bbl powered winter combo, and that is what I did.
IMO, this may be related to the fact that for all Torqueflites, the shiftsplits are NOT the same, but IDK that for sure;
1>2 is 1.45/2.45=.59 and
2>3 is 1.00/1.45= .69
The factory auto-shift calibration is pretty good for most of the time, but the WOT upshift rpms rarely match. If yur looking for that last lil bit of power, you gotta hold it with the manual shifter........ or fudge with the 1-2 spring.
What I discovered tho, is that when I did that, this also changed the 2>1 auto-downshift, which in my case, I really liked it.
I used to have to manually downshift for certain corners, before I got there, to be ready to power out of the turn. This was always a herky-jerky affair, so I had to do it before the turn, to prevent sliding.
After the change, now I go into the same turns in Second, and mid-turn, as I begin to lay on the power, bam the trans drops into First, all by itself, exactly at the right time! runs up to shift rpm, shifts, and we are outta there. and I never had to let go of the steering wheel.
But yeah, mine also has the PT kickdown, which now, actually works, which device can be retrofitted to any Torqueflite 67 or newer.
Oh and also worth mentioning is that my 904 runs a 2800 Stall. booyahh