Auto trans question

[InAccordance]

So I am wanting to be able to shift it manually into and out of first. With the weber, it's tough to get the cable set just right to keep it from shifting into 2nd early. I've got it rigged up and it does ok but still shifts into 2nd too early even at WoT. Really kills my acceleration times. I can get it delayed to about 4500rpm by being progressive with the gas pedal but it's tricky and doesn't always work. She'll take off like hell though when I do it just right :rockon:
Question is, is there a way to mod the shifter or linkage or whatever to have it so I can manually shift in and out of 1st?.

Thanks.