Hard shift to 2nd and 3rd

It might be easier and less frustration to just replace the valve body.
The shifts you are describing indicate that a stage 2 shift kit was installed and that means springs have been changed and the sepatator plate in the valve body has been drilled out.
If you just adjust the linkage after this has been done, you will never get it to work right.
A linkage adjustment will NEVER make it bang into gear unless fluid ports have been drilled.
Trust me on this one, as I have trans certifications up the you know what.
On my 904 I took the accumulator spring out and threw it away.
Drilled the 2nd gear band apply hole in the separator plate to 1/8 inch and adjusted my main line pressure to as high as it would go.
It now shifts nice and firm with a little tire chirp from first to second if I am on the gas more than the usual driving, and second to third is nice and quick but not hard.

Remember this,
The trans will NEVER bang into the next gear without drilled out oil flow ports or check balls removed to let the fluid travel to the clutches and bands faster and with more volume.

For second gear there is a chk ball that shift kits tell you to remove if you want a good hard shift, and some even instruct you to drill out one of the fluid track walls to get even more oil to the second gear band.
The point is that if your valve body has been modded, then you will never be able to adjust that out of it.
I think I have a pic of the ball they tell you to remove, so maybe you can at least tell by that if yours has been modded.

Here's a link to it with pics.
http://www.cuda-challenger.com/cc/index.php?topic=33093.0

If you see any of these mods in your valve body then it's been modded.
Especially note where the yellow ball is that they tell you to take out.
That is the second gear oil passage, and taking that ball out will make the trans bang into second.