Place it in drive.
Accelerate;
1st to 2nd shifts at about 35/40 mph.
2nd to 3rd shifts at 65 mph.
It really labors and hangs until you hit 65.

Okay - so lets go back to 1995...
I rebuilt a 727 for a 440, 10:1, .550 roller.
I used an article from one of the Mopar Mags;
Valve body: threw out some of the check balls and drilled out a hole here and there a little larger.
Accumulator Spring: I'm pretty sure I tossed it.
Line Pressure: I remember the article had me make a gauge out of cardboard and adjust the spacing to the gauge.
Torque Converter: 2500 stall.

This drive train never made it into my Road Runner; job change forced me to throw it in my 84 Crew Cab Dually with 4.10 rearend, to get from Utah to Tennessee. WHAT A BLAST OF A ROAD TRIP THAT WAS!!! Transmission worked great for running it hard.

Fast Forward to 2010: I never drove the truck after I got here. Now I'm at a point where I'm ready to play with the truck and drive it. I pulled out the built 440 and put in a bone stock 72 440 and a stock torque converter.

Finally - the question:
Of the 3 mods I did; valve body, accumulator spring, line pressue - which one mod, or combination there of, makes the late shifting point from 2nd to 3rd at 65 mph?

I'd love for the 2nd to 3rd shift point to be lower - like around 50 or 55.

Thanks in advance for the inputs!